HomeMy WebLinkAboutResolution 2021-112 N.C.S. 6/21/2021
Resolution No. 2021-112 N.C.S. Page 1
Resolution No. 2021-112 N.C.S.
of the City of Petaluma, California
RESOLUTION OF THE PETALUMA CITY COUNCIL ADOPTING VEHICLE MILES TRAVELED IMPLEMENTATION GUIDELINES PURSUANT TO CALIFORNIA SENATE BILL 743 WHEREAS, On January 11, 2021, the City Council and the Climate Action Commission adopted the Climate Emergency Framework, which guides the City’s ongoing response to and discussion about the climate crisis and establishes 2030 as the City’s goal for achieving carbon neutrality; and WHEREAS, under the California Environmental Quality Act (CEQA), cities, counties, and other public agencies must analyze discretionary projects to determine whether they may have a significant impact on the environment; and WHEREAS, traditionally, transportation impacts have been evaluated using a Level of Service (LOS)
analysis to determine whether discretionary projects are likely to cause automobile delay at intersections and congestion on nearby individual roadway segments; and WHEREAS, Senate Bill 743 (Steinberg), initiated a reform that established CEQA Guidelines Section 15064.3 requiring that lead agencies analyze transportation impacts of discretionary projects using the vehicle
miles traveled (VMT) metric instead of LOS, starting July 1, 2020; and WHEREAS, CEQA Guidelines Section 15064.3 defines vehicle miles traveled as the amount and distance of automobile travel attributable to a project; and WHEREAS, the Governor’s Office of Planning and Research (OPR) proposed, and the California Natural Resources Agency certified and adopted, new CEQA Guidelines Section 15064.3 that identified vehicle miles traveled as the most appropriate metric to evaluate a project’s transportation impacts; and WHEREAS, CEQA Guidelines Section 15064.7(a) defines a threshold of significance as “an identifiable
quantitative, qualitative, or performance level of a particular environmental effect, noncompliance with which means the effect will normally be determined to be significant by the agency and compliance with which means the effect normally will be determined to be less than significant”; and WHEREAS, CEQA Guidelines Section 15064.7(b) encourages lead agencies to adopt their own thresholds
of significance for the lead agency’s general use in its environmental review process and for local thresholds to be adopted by “ordinance, resolution, rule or regulation, and developed through a public review process and be supported by substantial evidence.”; and WHEREAS, pursuant to CEQA Guidelines Section 15064.7(c), when adopting thresholds of significance, “a
lead agency may consider thresholds of significance previously adopted or recommended by other public agencies provided the decision of the lead agency to adopt such thresholds is supported by substantial evidence”; and WHEREAS, the City of Petaluma did not adopt VMT Guidelines on or before July 1, 2020, but has been evaluating each subsequent project’s environmental impact related to transportation using OPR’s Technical
Advisory and recommendations therein including a VMT significance threshold of 15% below the per capita average, recommended screening criteria, and mitigation options; and
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WHEREAS, the City of Petaluma entered into a contract with Fehr & Peers on March 23, 2019, to conduct public outreach and develop VMT Implementation Guidelines to establish local thresholds, screening, and identify mitigation options; and
WHEREAS, the City of Petaluma formed a VMT Technical Advisory Committee (TAC) comprised of elected and appointed officials, City staff, a County representative, Caltrans representative, and staff from Sonoma County Transportation Authority; and WHEREAS, the VMT TAC convened on June 18, 2020, July 30, 2020, and March 30, 2021, for duly noticed public meetings and provided input and feedback on the key considerations and the Draft SB 743 Implementation Guidelines; and WHEREAS, at a duly noticed public hearing on May 25, 2021, the Planning Commission considered the
Draft SB 743 Implementation Guidelines including input from the VMT TAC and unanimously approved Resolution 2021-13 recommending that City Council adopt the Guidelines to bring the City into compliance with SB 743; and WHEREAS, through a public review process, the City of Petaluma developed local VMT Implementation
Guidelines, attached as Attachment 1, and identified VMT thresholds of significance for adoption; and WHEREAS, in accordance with CEQA Guidelines Section 15064.7(c) in developing the local VMT Implementation Guidelines consider thresholds of significance previously adopted or recommended by other public agencies or recommended by experts, provided the decision of the lead agency to adopt such thresholds is
supported by substantial evidence; and WHEREAS, in accordance with CEQA Guidelines Section 15064.7(b) the proposed local VMT Implementation Guidelines are supported by substantial evidence; and WHEREAS, the proposed local VMT Implementation Guidelines are an identifiable quantitative, qualitative or performance level approach to transportation analysis under CEQA; and WHEREAS, the City Council held a duly noticed public hearing on June 21, 2021, to consider the VMT Implementation Guidelines, at which time all interested parties had the opportunity to be heard; and
WHEREAS, public notice of the June 21, 2021, City Council hearing was posted on the City’s VMT and published in the Petaluma Argus-Courier on June 10, 2021; and WHEREAS, at said hearing, the City Council considered the staff report, dated June 21, 2021, and all public
testimony provided prior to and at the public hearing, input from the VMT TAC and Planning Commission on the Guidelines, and considered the Draft SB 743 Implementation Guidelines; and WHEREAS, adoption of VMT Implementation Guidelines including establishing VMT thresholds of significance will bring the City of Petaluma into compliance with SB 743 and closer to the Climate Emergency
Framework Goal of carbon neutrality by 2030; and WHEREAS, adoption of the Petaluma VMT Implementation Guidelines including establishing VMT thresholds of significance, screening criteria, and mitigation options is not considered a “project” pursuant to CEQA Guidelines Section 15378(a) as the action of adopting thresholds of significance is not a project because
it does not constitute a direct physical impact on the environment, nor would it result in an indirect, reasonably foreseeable physical impact on the environment; and
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WHEREAS, the City of Petaluma is mandated to comply with SB 743 and CEQA Guidelines Section 15002(i)(1) states “where the law requires a government agency in a set way without allowing the agency to use its own judgement, the project is called ‘ministerial’ and CEQA does not apply,” accordingly the action of
adopting VMT Implementation Guidelines is therefore considered ministerial and is not subject to CEQA review; and WHEREAS, even if Adoption of the Petaluma VMT Implementation Guidelines including establishing VMT thresholds of significance, screening criteria, and mitigation options did meet the definition of a “project” under
CEQA, it qualifies for a Class 8 categorical exemption (Actions by a Regulatory Agency for Protection on the Environmental) in accordance with Section 15308 of the State CEQA Guidelines as the proposed CEQA threshold complies with a state mandate (SB 743), exceeds the Office of Planning and Research’s recommended VMT threshold of 15% below the per capita average, and will be used in a regulatory process (CEQA review) that involves procedures for the protection of the environment. NOW, THEREFORE, BE IT RESOLVED by the City Council of the City of Petaluma as follows: 1. Declares the above recitals to be true and correct and are incorporated herein as findings.
1. Based on its review of the entire record herein, adoption of the VMT Implementation Guidelines is not subject
to CEQA based on the following findings: a. Adoption of the Petaluma VMT Implementation Guidelines including establishing VMT thresholds of significance, screening criteria, and mitigation options is not considered a “project” pursuant to CEQA Guidelines Section 15378(a). The action of adopting thresholds of significance is not a project because it does not constitute a direct physical impact on the environment, nor would it result in an indirect,
reasonably foreseeable physical impact on the environment. b. The City of Petaluma is mandated to comply with SB 743. CEQA Guidelines Section 15002(i)(1) states “where the law requires a government agency in a set way without allowing the agency to use its own judgement, the project is called ‘ministerial’ and CEQA does not apply.” The action of adopting VMT Implementation Guidelines is therefore considered ministerial and is not subject to CEQA review.
c. Even if Adoption of the Petaluma VMT Implementation Guidelines including establishing VMT thresholds of significance, screening criteria, and mitigation options did meet the definition of a “project” under CEQA, it qualifies for a Class 8 categorical exemption (Actions by a Regulatory Agency for Protection on the Environmental) in accordance with Section 15308 of the State CEQA Guidelines. The CEQA threshold complies with a state mandate (SB 743), exceeds the Office of Planning and Research’s
recommended VMT threshold of 15% below the per capita average, and will be used in a regulatory process (CEQA review) that involves procedures for the protection of the environment. 2. Based upon staff and consultant reports and research as well as testimony in the record, that the CEQA thresholds of significance under consideration went through a public review process, are consistent with State
requirements as to how transportation impacts should be evaluated for purpose of CEQA review and are supported by substantial evidence. The significance thresholds for transportation are based upon the VMT metric consistent with CEQA Guidelines Section 15064.3. The City is setting the VMT thresholds at a level that meets or exceeds OPR guidance.
3. Adopts the Draft VMT Implementation Guidelines including “Vehicle Miles Traveled” thresholds of significance for purposes of analyzing transportation impacts under CEQA, attached hereto as Attachment 1.
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Under the power and authority conferred upon this Council by the Charter of said City.
REFERENCE: I hereby certify the foregoing Resolution was introduced and adopted by the
Council of the City of Petaluma at a Regular meeting on the 21st day of June
2021, by the following vote:
Approved as to
form:
__________________________
City Attorney
AYES: Mayor Barrett; Vice Mayor Barnacle; Fischer; King; McDonnell; Pocekay
NOES: Healy
ABSENT: None
ABSTAIN: None
ATTEST: ______________________________________________
City Clerk
______________________________________________
Mayor
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Senate Bill 743
Vehicle Miles Traveled
Implementation Guidelines
[DRAFT]
Prepared for:
City of Petaluma
May 17, 2021
SF19-1023
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ATTACHMENT 1
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Table of Contents
Executive Summary ........................................................................................................................ i
1. Introduction ............................................................................................................................... 1
2. Background ................................................................................................................................ 2
2.1 Definitions ................................................................................................................................................................................ 2
2.2 VMT Policy Overview ........................................................................................................................................................... 2
2.3 VMT Adoption Process Overview ................................................................................................................................... 4
2.4 VMT Assessment Overview ............................................................................................................................................... 6
2.4.1 VMT Metrics ................................................................................................................................................................ 8
2.4.2 VMT Methods ...........................................................................................................................................................10
2.4.3 Baseline VMT ............................................................................................................................................................13
2.4.4 Factors Influencing VMT Estimates and Forecasts .....................................................................................14
2.4.5 VMT Thresholds .......................................................................................................................................................15
2.4.6 Screening Criteria ....................................................................................................................................................17
2.4.7 Mitigating VMT Impacts .......................................................................................................................................17
3. Implementation Recommendations ...................................................................................... 20
3.1 Metrics .....................................................................................................................................................................................20
3.2 Methods .................................................................................................................................................................................20
3.3 Thresholds of Significance ..............................................................................................................................................21
3.4 Screening Criteria................................................................................................................................................................22
3.5 Mitigation Options .............................................................................................................................................................24
3.6 CEQA VMT Transportation Impact Analysis Guidelines ......................................................................................24
3.7 Disruptive Trend Impacts on VMT Estimation .........................................................................................................25
4. TDM Strategy Research .......................................................................................................... 27
4.1 Recommended VMT Reduction Strategies ..............................................................................................................29
4.1.1 Project/Site Level Strategies ...............................................................................................................................29
4.1.2 City/Community Level Strategies .....................................................................................................................30
4.2 Combining VMT Reduction Strategies .......................................................................................................................32
4.3 Implementing VMT Reduction Strategies .................................................................................................................33
5. Considerations for Updating Recommendations ................................................................ 36
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Appendices
Appendix A: Trip Length Adjustments for SB 743 VMT Analysis
Appendix B: CEQA VMT Transportation Impact Analysis Guidelines
Appendix C: Methodologies to Quantify VMT Reductions
Appendix D: CAPCOA Guidance on Combining TDM Strategies
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Executive Summary
This report summarizes the recommendations and outcomes of the City of Petaluma’s efforts to
implement vehicle-miles traveled (VMT) as the California Environmental Quality Act (CEQA) Transportation
analysis metric, pursuant to Senate Bill 743 (Steinberg, 2013) and corresponding updates to the CEQA
Guidelines effective April 2019. Per Senate Bill 743, congestion-related metrics such as automobile Level
of Service (LOS) shall no longer be used in CEQA Transportation analysis for land use projects; instead,
VMT has been identified as the most appropriate metric for the evaluation of CEQA Transportation
impacts.
The City of Petaluma’s implementation efforts included the formation of a Technical Advisory Committee
(TAC) comprised of liaisons from the City Council, Planning Commission, City committees/ commissions
(Climate Action Commission, Bicycle and Pedestrian Committee, and the Transit Advisory Committee), City
departments, and other regional transportation agencies (Caltrans, Permit Sonoma, and Sonoma County
Transportation Authority). As part of three public meetings, the TAC reviewed materials related to key
decision points in the implementation process and developed recommendations on how to proceed with
implementing VMT for land use project, land use program, and local transportation infrastructure analysis
in Petaluma. Additionally, the public was invited to provide feedback at the TAC meetings and via email.
Based on their review of key implementation decisions, the TAC recommends implementing the following
key decisions for SB 743 in Petaluma:
• VMT metrics - “What VMT should be measured in traffic analyses?”:
o Residential projects: Total home-based VMT per resident
o Office and other employment-focused projects: Total home-based work VMT per employee
o Retail and other commercial service projects: Total project effect on VMT within a geographic area
• VMT methods – “How should VMT be calculated?”: Use the SCTA travel demand model.
• VMT thresholds – “At what point does project VMT require mitigation?”:
o For residential projects: Project total home-based VMT per resident exceeds 83.2% of the
citywide average. The City-wide average baseline value applies until such time that the City of Petaluma exceeds the housing allocation for the City as identified in the
Sustainable Communities Strategy (SCS) for the Bay Area region; if the City exceeds the
SCS housing allocation, the nine-county Bay Area regional average applies.1
1 The SCS housing allocation limit is suggested by the California State Office of Planning and Research (OPR) in the Technical Advisory on Evaluating Transportation Impacts in CEQA as when the use of a citywide average becomes inappropriate for the evaluation of CEQA VMT impacts (in favor of the Bay Area regional average).
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o For office and other employment-focused projects: Project total home-based work VMT per
employee exceeds 83.2% of the nine-county Bay Area regional average.
o For retail and other commercial service projects: Project results in a net increase in VMT over the geographic area that the project influences.
o For mixed-use and other projects: Project components should be analyzed using the relevant thresholds for residential, office/employment-focus, or retail/commercial service
projects. The benefit of a mix of uses on-site can and should be included in the analysis.
o For transportation projects: Project results in induced travel and an increase in citywide VMT.
o For redevelopment projects: Project results in increased VMT versus current land uses. City
staff retain discretion to identify the baseline VMT for use in the calculation (i.e. based on current uses or permitted uses).
• VMT screening criteria – “What projects may qualify for bypassing the VMT analysis process?”:
o Small Projects: Projects that generate or attract fewer than 110 trips per day, which is
equivalent to a 15-unit residential project or a non-residential project of 10,000 square feet or less. Local-serving retail projects of less than 30,000 square feet may be screened
on the basis that they may attract trips that would otherwise travel longer distances.
o Projects in Low-VMT Area: Residential and office/employment-focused projects that are in low-VMT areas (based on adopted VMT thresholds of significance) that are similar in
similar to nearby developments in terms of density, mix of uses, and transit accessibility.
o Projects in Proximity to a Major Transit Stop: Projects within one-half mile of an existing or planned high-quality transit corridor or major transit station. Several additional criteria
related to site design, parking supply and consistency with regional transportation plans must be met in order to qualify for this screening opportunity.
o Affordable Housing in Jobs-Rich Areas: Projects that include 100 percent affordable
housing that are located in infill locations and areas with a high jobs-housing imbalance.
o Transportation Projects: Transit, bicycle, and pedestrian projects, and roadway
maintenance projects that do not result in an increase in vehicle capacity or VMT.
o Projects including a drive-through component would be precluded from qualifying for screening out of VMT analysis process.
o City staff retains discretion to deny the use of screening if substantial evidence exists that screening is not appropriate for a given project.
• VMT mitigation options – “How should a project mitigate a significant impact?”:
o Near-Term: Perform mitigation on a project-by-project basis using available TDM effectiveness research. TDM strategies related to promoting transit usage, active
transportation, and more sustainable parking strategies should be prioritized.
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o Medium-Term: The City should investigate and implement citywide TDM programs and
fund these programs through developer fees.
o Far-Term: The City should coordinate with SCTA and other agencies in Sonoma County to develop a VMT mitigation banking program, should pilot programs in Contra Costa
County and Southern California prove successful.
Pursuant to Section 15064.7 of the CEQA Guidelines, the VMT thresholds of significance will be adopted
by the City Council as part of an ordinance, resolution, rule or regulation. The City will review the
thresholds of significance after completing the City of Petaluma’s General Plan and Climate Action Plan and update these thresholds if they are inconsistent with the City’s goals for reducing greenhouse gas and
VMT.
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1. Introduction
On September 27, 2013, Governor Jerry Brown signed Senate Bill (SB) 743 into law and started a process
intended to fundamentally change transportation impact analysis as part of California Environmental
Quality Act (CEQA) compliance. These changes include elimination of auto delay, level of service (LOS), and
other similar measures of vehicular capacity or traffic congestion as a basis for determining significant
impacts. Amendments and additions to the CEQA Guidelines eliminate auto delay for CEQA purposes and
identify vehicle miles traveled (VMT) as the preferred CEQA transportation metric. Therefore, the City of
Petaluma carried out a public process to select VMT analysis methodologies, set new VMT thresholds for
transportation impacts, and determine what mitigation strategies are most feasible.
This report:
• Provides an overview of SB 743 and related policies and how VMT may be measured
• Discusses the public review and adoption process undertaken by the City of Petaluma • Discusses alternatives for VMT measurement methods and thresholds
• Recommends VMT methods and thresholds for Petaluma, based on feedback from the City’s
Technical Advisory Committee formed for this SB 743 implementation effort
• Uses recent projects in Petaluma to demonstrate how these methods and thresholds would be
used
• Recommends transportation demand management (TDM) strategies for reducing VMT on
projects in Petaluma • Provides information on considerations resulting in future updates to the recommendations in
this document
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2. Background
This chapter summarizes SB 743 and related policies and discusses how VMT may be measured.
2.1 Definitions
CEQA refers to the California Environmental Quality Act. This statute requires identification of any
significant environmental impacts of state or local action including approval of new development or
infrastructure projects. The process of identifying these impacts is typically referred to as the
environmental review process.
LOS refers to “Level of Service,” a metric that assigns a letter grade to network performance. The typical
application of LOS in Petaluma is to measure the average amount of delay experienced by vehicle drivers
at an intersection during the most congested time of day and to assign a report card range from LOS A
(fewer than 10 seconds of delay for signalized intersections) to LOS F (more than 80 seconds of delay for
signalized intersections). The City of Petaluma’s LOS standard (as identified in the General Plan) is LOS D.
VMT refers to “vehicle miles traveled,” a metric that accounts for the number of vehicle trips generated
and the length or distance of those trips. For transportation impact analysis, VMT is commonly expressed
as total VMT, total VMT per service population (residents plus employees), home-based VMT per resident
(or capita), and home-based work VMT per employee for a typical weekday.
2.2 VMT Policy Overview
On September 27, 2013, Governor Jerry Brown signed SB 743 into law and started a process intended to
fundamentally change transportation impact analysis as part of CEQA compliance. These changes include
elimination of auto delay, LOS, and other similar measures of vehicular capacity or traffic congestion as a
basis for determining significant impacts. The California Natural Resources Agency has issued
amendments and additions to the CEQA Guidelines reflecting these changes
(http://resources.ca.gov/ceqa/). The changes eliminate auto delay for CEQA purposes and identify VMT as
the preferred CEQA transportation metric.
The Governor’s Office of Planning and Research (OPR) has also issued supporting information entitled
Technical Advisory on Evaluating Transportation Impacts in CEQA (December 2018)
(http://opr.ca.gov/ceqa/updates/sb-743/), providing additional information on assessing VMT and setting
significance thresholds.
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The focus of SB 743’s changes can be found in the following two legislative intent statements:
1. Ensure that the environmental impacts of traffic, such as noise, air pollution, and safety concerns,
continue to be properly addressed and mitigated through the California Environmental Quality
Act.
2. More appropriately balance the needs of congestion management with statewide goals related to
infill development, promotion of public health through active transportation, and reduction of
greenhouse gas emissions.
These statements are important because they provide direction to OPR and to lead agencies. For OPR, the
direction is largely about what new metrics should achieve. For lead agencies like the City of Petaluma, the
direction is about expected changes in transportation analysis plus what factors to consider for
significance thresholds.
SB 743 does not prevent an agency from continuing to analyze delay or LOS as part of other plans (i.e. a
general plan), fee programs, or ongoing network monitoring, but these metrics will no longer constitute
the sole basis for CEQA impacts. Agencies determining that continued use of vehicle LOS is an important
part of transportation analysis can still use vehicle LOS outside of the CEQA process. The most common
applications will likely occur for jurisdictions wanting to use vehicle LOS to size roadways in their general
plan or determine nexus relationships for their impact fee programs. Jurisdictions can also continue to
condition projects to build transportation improvements through the entitlement process in a variety of
ways, such as using general plan consistency findings.
The changes to the CEQA Guidelines identify automobile2 VMT as the preferred CEQA transportation
metric and, upon their certification on December 28, 2018, eliminated use of auto delay and LOS
statewide for CEQA transportation analysis. The new guidelines and the OPR technical advisory include
specifications for VMT methodology and recommendations for significance thresholds and mitigation. As
noted above, SB 743 requires impacts to transportation network performance to be viewed through a
filter that promotes “the reduction of greenhouse gas emissions, the development of multimodal
transportation networks, and a diversity of land uses.” VMT can help identify how projects (land
development and infrastructure) influence accessibility (i.e., lower VMT may indicate increased multimodal
access to places and people) and emissions, so its selection is aligned with the objectives of SB 743.
Caltrans routinely reviews CEQA documents for local agency development projects. In this role, Caltrans is
either a commenting agency or a responsible agency under CEQA (see CEQA §21069) and sets
expectations for adequate analysis of the State highway system. Caltrans recently released an update to
2 Automobile includes passenger cars and light trucks. However, OPR’s Technical Advisory allows VMT analysis to include all vehicles (i.e., commercial trucks) for calculation convenience purposes.
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their Transportation Impact Study Guide (TISG) (https://dot.ca.gov/-/media/dot-
media/programs/transportation-planning/documents/sb-743/2020-05-20-approved-vmt-focused-tisg-
a11y.pdf). Key points from this draft include the following:
• Caltrans recommends use of OPR’s recommended thresholds for land use projects.
• Caltrans supports CEQA streamlining for land use projects in transit priority areas and areas with
existing low VMT, as described in OPR’s Technical Advisory.
• Caltrans recommends following the guidance on methods of VMT assessment found in OPR’s
Technical Advisory.
• Caltrans comments on a CEQA document may note methodological deviations from those
methods and may recommend that significance determinations and mitigation be aligned with
state GHG reduction goals as articulated in that guidance, California Air Resources Board’s (ARB’s)
2017 Climate Change Scoping Plan Update: The Strategy for Achieving California’s 2030
Greenhouse Gas Target (2017), and related documentation.
• In rural areas, Caltrans may request VMT-reducing strategies for the rural area be included
programmatically, including at the General Plan level, for example. Caltrans will also recommend
establishment of programs or methods to reduce VMT and support appropriate bicycle,
pedestrian, and transit infrastructure, services or incentives.
If a lead agency chooses a different threshold, but want to provide information to more directly satisfy
potential Caltrans comments, they may have to complete more than one impact analysis.
In July 2020, Caltrans released interim guidance to its districts on how to review potential safety impacts
for projects that affect the state highway system (https://dot.ca.gov/-/media/dot-
media/programs/transportation-planning/documents/sb-743/2020-07-01-interim-ldigr-safety-guidance-
a11y.pdf). Similar to VMT analysis, safety analysis for CEQA purposes is a rapidly evolving topic. While the
focus of the SB 743 is on implementing VMT for CEQA, it is recommended that the City also review how
Caltrans’s safety analysis guidance may affect environmental documents in the future given the presence
of US 101 and State Route 116 (Lakeville Highway) in the City. It is expected that Caltrans will apply this
guidance when reviewing activities that affect Caltrans facilities. As such, it is recommended that the City
require safety analysis for projects that add trips to the state highway system in the future; safety analysis
methods and criteria will be developed as part of a future implementation effort (i.e. after VMT is
implemented).
2.3 VMT Adoption Process Overview
CEQA Guidelines Section 15064.7 governs the establishment of thresholds of significance for CEQA
analyses. For the purposes of the adoption of VMT-based CEQA Transportation analysis thresholds of
significance, the following subsections are of particular note.
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(b) Each public agency is encouraged to develop and publish thresholds of significance that the agency uses in the determination of the significance of environmental effects. Thresholds of significance to be adopted for general use as part of the lead agency's environmental review process must be adopted by ordinance, resolution, rule, or regulation, and developed through a public review process and be supported by substantial evidence. Lead agencies may also use thresholds on a case-by-case basis as provided in Section 15064(b)(2).
(c) When adopting or using thresholds of significance, a lead agency may consider thresholds of significance previously adopted or recommended by other public agencies or recommended by experts, provided the decision of the lead agency to adopt such thresholds is supported by substantial evidence.
The City of Petaluma has undertaken a public review process to inform adoption of general use VMT
thresholds at a City Council meeting through the passage of an ordinance, resolution, rule or regulation. A
critical component of the public review process has been the formation of a Technical Advisory
Committee (TAC), which was comprised of the following members:
• Appointed Council and Commission Liaisons
o D’Lynda Fischer – Vice Mayor, Council Liaison
o Sandi Potter – Planning Commission Liaison3
o Sean Walling – Pedestrian and Bicycle Advisory Commission Liaison
o Panama Bartholomy – Climate Action Commission Liaison
o Dave Alden – Transit Advisory Committee Liaison
• Petaluma City Staff Liaisons
o Gina Benedetti-Petnic – City Engineer
o Jeff Stutsman – Traffic Engineer
o Jared Hall – Transit Manager
• Other Agency Liaisons
o Chris Barney – Sonoma County Transportation Authority
o Gary Helfrich – Permit Sonoma
o Andrew Chan – Caltrans
Three public meetings with the TAC occurred over the course of the adoption effort, including on June 18,
2020, July 30, 2020 and March 30, 2021. TAC members discussed the various options for implementation
of SB 743 and adoption of VMT-based CEQA thresholds of significance. Members of the public were also
invited to make public comments, consistent with typical procedures associated with public meetings
governed by the Brown Act. The recommendations of the TAC are summarized in the next chapter of this
report.
3 Patrick Streeter served as Planning Commission Liaison for the June and July 2020 TAC meetings. Sandi Potter served as Planning Commission Liaison for the February 2021 TAC meeting.
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2.4 VMT Assessment Overview
VMT can be measured in a variety of ways depending on whether the intent is to capture the amount of
vehicle travel generated by a project (i.e., number of vehicle trips multiplied by their corresponding trip
lengths) or a project’s effect on VMT within a defined study area. Project effect information is more
meaningful for VMT analysis because land use projects and land use plans often influence the vehicle
travel associated with neighboring land uses. Figure 1 illustrates the difference between these two types
of VMT.
VMT is a preferred metric for environmental effects because it captures how a project influences the
environment related to fuel consumption and emissions while also serving as an indicator of potential
impacts to pedestrians, bicyclists, transit riders, and travel safety.
VMT growth associated with land use and transportation projects is part of adopted regional
transportation plans (RTPs) and general plans. These plans typically consider the acceptability of VMT
growth at a cumulative or programmatic level. Additional VMT reduction may be achieved at the project
level especially through TDM strategies, which are not fully accounted for in regional level travel
forecasting models.
Although VMT is focused on vehicle travel, the goal of reducing per capita VMT growth rates leads to an
emphasis on the effects of development patterns (e.g., land use mix and density) together with
pedestrian, bicycle, and transit infrastructure. These factors have an impact on the number and length of
vehicle trips. Efforts to reduce VMT may also include TDM strategies that encourage more efficient forms
of travel or vehicle use.
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Measuring Vehicle Miles Traveled (VMT)
Figure 1
Project Limits/Jurisdiction Limits
Notes: External to External (XX) trips are excluded from this VMT metric.
Adjustments to project generated VMT made to include the full length
of trips that leave the jurisdiction to capture inter-jurisdiction travel.
1
2
3
Project Generated VMT
4
Project Effect on VMT
(Boundary VMT)
Notes: Boundary VMT is all the VMT on the streets within the Project Limits /
Jurisdiction Limits.
External to Internal (XI) VMT
Internal to External (IX) VMT Internal to Internal VMT1
2
3
External to External (XX) VMT4 External to Internal (XI) VMT
Internal to External (IX) VMT 2x Internal to Internal (2xII) VMT1
2
3
External to External (XX) VMT4
Project Limits/Jurisdiction Limits
3
1
2
4
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2.4.1 VMT Metrics
Metrics refer to the types of VMT that are captured in the calculations to be performed as part of the
CEQA process. For example, trip types can be broken down by trip purpose, such as home-work, home-
other and other-other (i.e. trips with neither a start nor end at a residence). Because the CEQA Guidelines
focus analysis on (personal) automobile trips, OPR has given guidance (in the Technical Advisory) that
metrics for most residential and office (i.e. employment-focused) projects should analyze the portion of
the VMT attributable to a project that is focused on travel by personal automobiles. Further, the partial
VMT calculated should be divided by the number of residents or employees to arrive at a per capita
efficiency metric to provide a point of comparison between the project being analyzed and other similar
developments in the city or region
New land use projects accommodate population and employment growth; this growth generates new
VMT (e.g., a new office building resulting from a land use rezone will generate new vehicle trips and VMT).
Whether a project contributes to a more efficient land use pattern (i.e., one that requires less vehicle travel
compared to similar land uses) can be determined by using a VMT efficiency metric. Efficiency metrics
express a total increase in VMT relative to the increase in residents and employees (VMT per resident, or
VMT per worker). Total project-generated VMT as a stand-alone metric tends to be more relevant as an
input to Air Quality, Greenhouse Gas, and Energy consumption impact analysis.
VMT efficiency metrics can be further disaggregated into specific types of VMT and populations, such as
considering only the VMT generated by residents making trips to and from home. Each of the VMT
efficiency metrics listed below addresses a slightly different question in terms of impact analysis. Table 1
(presented below) also provides a primer on what types of VMT are captured under each category.
• Home-based VMT per resident measures VMT generated by trips that have an origin or destination at a home location and reflects how close households are to common destinations, as
well as the available transportation options. Because the trip type is specific to local residents, it
helps compare residential projects across different locations. However, it omits many different trip types (such as a trip made from a work location to a retail location or trip made by a delivery
driver to a residence) and is considered a “partial” VMT metric.
Answers the question: Do people living here drive more or less on average compared to other places?
• Home-based work VMT per employee reflects how close a workplace is to places where
employees live. Because the trip type is specific to work trips, it helps compare office or other employment projects across different locations. However, it omits many different trip types (such
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as a trip made by an employee traveling from work to the grocery store) and is considered a
“partial” VMT metric.
Answers the question: Do people working here drive more or less during their commutes compared to workers in other places?
• Total project-generated VMT per service population provides a more comprehensive understanding of VMT than the home-based per resident or home-based per employee, which
are partial VMT metrics. By taking the total VMT to and from a project or geographic area and
dividing it by the total number of residents plus the total number of employees, a comparison of how VMT intensive the project is as a whole can be made. For example, this metric would capture
delivery trips to and from residences and businesses, which may be a substantially more
considerable VMT source in the coming years.
One caveat for total VMT per service population is that employment-based uses generate more total VMT than non-employment uses, so projects with more employment may have a higher
VMT rate by this metric. Further, the VMT associated with employees also includes VMT
generated by visitors and customers. Retail and commercial land uses, therefore, generate disproportionately higher levels of VMT per employee.
Answers the question: Is this area or project as a whole more or less VMT intensive than other
places?
• Total project effect on VMT assesses whether a project would cause a net increase or net
decrease in VMT within the boundary of a geographic area, compared to a no project condition.
Because the total project effect on VMT does not hinge on the ratio of residents to employees, it provides the most direct way of understanding how development would change local travel
patterns. To reflect a project’s effects, the boundary area should include full trip lengths and not be truncated at political or model boundaries.
Answers the question: What effect would building this project have on the way people travel in
Petaluma/Sonoma County/and the region? Would there be a net increase or net decrease in regional VMT compared to building a similar project elsewhere?
These potential VMT metrics were submitted to the TAC for review and discussion and to facilitate the
development of a recommendation for adoption. TAC recommendations for adoption are presented in
Section 3.1 of this report.
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Table 1: Illustration of Common Types of VMT
Vehicle Trip Type Examples Included in Home-Based VMT?
Included in Home-Based Work VMT?
Included in Total VMT?
Petaluma Land Use Generated Boundary Method1
A Petaluma resident drives directly from home to their workplace X X X
A Petaluma employee drives directly from home to work X X X
A Petaluma resident drives their child from home to soccer practice X X X
A Petaluma resident drives their child from school to soccer practice X
A Petaluma employee drives from work directly to the grocery store X X
A San Rafael resident drives from home to Santa Rosa through Petaluma, using US 101 or using city streets.
X
A Novato resident travels to Downtown Petaluma to eat out X X
A South San Francisco resident travels to the Petaluma to visit a family member who resides there X X
Amazon delivers to a resident of the Petaluma X X
Amazon delivers to an employer in the Petaluma X X
OPR recommendation for use? Residential Projects Employment- Focused Projects Not Recommended Retail Projects
1. Boundary method VMT assumes that SCTA model trip lengths at the boundaries of Sonoma County are appropriately calibrated for these trips. Source: Fehr & Peers, 2020
2.4.2 VMT Methods
VMT methods refer to the manner in which VMT is calculated for project analysis purposes. For cases in
which a project is not screened from a quantitative VMT analysis, a consistent methodology for
calculating VMT should be developed. Travel forecasting models such as the Sonoma County
Transportation Authority (SCTA) travel model are the most appropriate method for calculating VMT since
they can produce forecasts for the project’s effect on VMT and account for changes in travel behavior.
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The matrix in Table 2 (presented on the next page) contains a comparison of three travel forecasting
models with geographies that overlap with Petaluma. These models include the City of Petaluma model,
the SCTA model, and the Metropolitan Transportation Commission (MTC) model. The matrix includes
relevant evaluation criteria for each model and compares the applicability of each model for forecasting
VMT within Petaluma. As described in the matrix in Table 2, the SCTA travel model was recommended as
the forecasting model for producing VMT forecasts in Petaluma. TAC recommendations for adoption are
presented in Section 3.2 of this report.
The SCTA model may be used to calculate the VMT metrics described above if the project is large enough
for the model to be sensitive to changes in land use.4 Ideally, this would consist of calculating total
project-generated VMT, total citywide or County VMT, and VMT per employee/resident for model
scenarios with and without the project. Impacts could be assessed based on both efficiency metrics (e.g.,
home-based VMT per resident) as well as the project’s effect on VMT (the total change between no
project and plus project scenarios). Because Petaluma is located near the edge of the SCTA model
boundaries, VMT reported by the model should be adjusted to account for VMT that extends beyond the
model limits (e.g., from Petaluma to San Rafael, which is outside the SCTA boundary). These adjustments
should include adding an average trip length for vehicle trips leaving the model area based on data from
the Sonoma County Travel Behavior Study, California State Travel Demand Model, the California
Household Travel Survey, mobile devices, or the US Census Bureau; the version of the SCTA travel demand
model (build date August 2020) has been adjusted for data in the Sonoma County Travel Behavior Study,
and thus the VMT estimates from the model generally account for county boundary effects.
Appendix A describes the general methodologies and data sources for making these adjustments; it is
noted that while the SCTA model has been updated to reduce the effects of trip length truncation, the
City should encourage preparers of traffic studies to use judgement in determining if the VMT estimates
from the model are appropriately accounting for trip lengths across the county boundary.
Mixed-use projects should be analyzed using the SCTA model to assess the project’s effect on VMT and
report home-based VMT per resident and home-based work VMT per employee for residential and office
components, respectively. Home-based VMT per resident may also be useful for other uses with similar
travel characteristics, such as hotels or group quarters. Home-based work VMT per employee may be
useful for other uses similar to employment, such as schools, universities, etc.
4 Model calibration and sensitivity testing should occur as part of any analysis involving travel demand model runs.
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Table 2: Petaluma SB 743 Implementation – Travel Forecasting Model Comparison
Evaluation Criteria City of Petaluma Model SCTA Model MTC Model
Model Structure 3-Step Trip-Based Model No Mode Split Step 4-Step Trip-Based Model With Mode Split Step Activity-Based Model Auto-Ownership Model
Calibration Year1 2007 2015 2010
Model Detail within Petaluma
High: 383 TAZs and 2,146 Links
Medium: 82 TAZs and 733 Links
Low: 9 TAZs and 173 Links
Model Boundaries
Petaluma City Limits
Sonoma County Limits
Nine-County Bay Area
Level of Petaluma Trips Truncated at Model Boundaries
High: All trips leaving Petaluma City Limits are truncated.
Low: All trips leaving Sonoma County limits are truncated, however Big Data is used to account for the truncated portion of trips.
Low: Only trips leaving Nine-County Bay Area are truncated.
Model Run Time <1 hour ~1 hour ~24 hours
Key Limitations Requiring Action
Updated model calibration and validation is necessary to accurately assess VMT impacts. The update would require substantial time and cost.
Modelers should review model trip lengths to confirm capture of full length of trips
Model sensitivity to local project land use changes is untested. Changing model inputs for land use projects requires substantial time and cost.
Recommendation
Not Recommended: - High level of truncated trips - Model requires substantial update and recalibration - No mode split step
Recommended: - Petaluma is member agency - Most recent calibration - Supplemented with empirical data (i.e., Big Data) - SCTA has consistently provided model maintenance and updates
Not Recommended: - Coarse model detail in off-the-shelf version - Unknown model accuracy and sensitivity for local projects - Time consuming to make land use changes - Long run time
Source: Fehr & Peers, 2020. Notes: 1. Model should be calibrated within the past five years.
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Some land use components (e.g. retail, restaurant, entertainment, recreation) may be assessed
qualitatively if they serve primarily local trips. Particularly for retail uses, a qualitative discussion of how
the uses would primarily serve local trips may be adequate to determine the project’s effect on VMT.
Otherwise, based on guidance in the OPR Technical Advisory, retail projects should be assessed based on
the project’s effect on VMT.
Some projects may not be large enough for the SCTA model to be sensitive to the changes they
represent, but too large to qualify for small project screening. In these cases, spreadsheet-based methods
based on a VMT generation rate for the project’s TAZ may be useful. This method works well when the
proposed project is similar to the types of land uses already present in the TAZ (for instance, adding a new
multi-family development to a residential zone). If the project is small, and somewhat unique for the area
in which it is proposed, additional data may need to be collected.
Other alternatives for assessing the VMT effects of smaller projects are to further validate a sub-area
model (which requires additional time and effort for analysis and may be expensive), or to use a sketch
planning tool such as CalEEMod or MXD+ that have been modified to reflect trip generation rates and trip
lengths consistent with the SCTA model used to set thresholds.
The determination of whether a project requires a qualitative, sketch-level, or model-level assessment will
be made during the environmental scoping process.
2.4.3 Baseline VMT
Baseline VMT information is dependent on the time that the project is deemed complete or a Notice of
Preparation (NOP) for an environmental document is released, as well as the selected metric(s) and
method to be applied for the VMT analysis of a given project. Table 3 (located on the next page) presents
baseline information derived from the SCTA travel demand model for Year 2015 conditions for a variety of
VMT metrics. Table 3 also includes examples of how the baseline VMT information could translate into
thresholds of significance based on common threshold choices from agencies throughout California. It is
noted that these baseline VMT values are subject to change as time progresses, and that future VMT
analyses should carefully consider whether the baseline information in Table 3 remains applicable and/or
is relevant for a given project. For example, the Year 2015 base year model data may be reasonable for
use in some parts of Sonoma County due to the effects of the 2017 and 2019 wildfires, as well as the
economic and travel behavior effects of the COVID-19 pandemic in 2020.
It is noted, however, that the Year 2015 base year model does not include the effects of the SMART
passenger rail system that opened in 2017. While the effects of the lack of SMART passenger rail in the
model on VMT estimates are not precisely known, the lack of SMART passenger rail represents a
conservative assumption because it assumes more overall driving in the model in the near-term analysis
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horizon scenario. By doing so, the model amplifies the VMT effects on projects, thus leading to a more
conservative assumption. In the course of a traffic analysis, the City can qualitatively assess how SMART
passenger rail affects the VMT calculation or the calculation of the effectiveness of VMT-related mitigation
measures.
Table 3: City of Petaluma Baseline VMT by VMT Metric
VMT Metric Baseline VMT
VMT Threshold Options
OPR 15% Below Baseline ARB 16.8% Below Baseline Any Net VMT Increase1
Home-Based VMT per Resident Citywide Average 19.3 16.4 16.1 n/a
Home-Based Work VMT per Employee Nine-County Bay Area Average 22.7 19.3 18.9 n/a
Total VMT per Service Population Citywide Average 36.7 31.2 30.5 n/a
Total VMT within city limits1
City generated VMT + pass-through 1,185,199 n/a n/a 1,185,199
Notes:
1. A threshold of any net increase in VMT is most appropriate when analyzing total VMT and the possibility for induced vehicle travel resulting from transportation improvement projects. It may also be useful for assessing retail and other local-serving land use projects.
Source: SCTA Travel Demand Model (August 2020); Fehr & Peers, 2020.
2.4.4 Factors Influencing VMT Estimates and Forecasts
Estimates of current VMT and forecasts of future VMT are inherently dependent on the methodology
used. These estimates and forecasts may not account for recent changes in economic activity, or future
trends such as greater transportation network company (TNC) use through autonomous vehicles (AVs).
Prior to COVID-19, expectations about the influence of these factors is that vehicle travel is likely to
increase over time as the human driving function is eliminated, operating and parking costs are reduced,
and access to a variety of vehicle types becomes more ubiquitous. Immediate COVID-19 effects that have
challenged these expectations include a shift to work-from-home for many office-located jobs, an
increased use in online retail and entertainment, and a desire for recreational activities that allow for
spacing between individuals. These VMT-suppressing factors may be counteracted in part or in whole by a
slow recovery in public transit usage. Ultimately, VMT trends will need to be monitored over time as
COVID-19 economic outcomes may dampen these expectations.
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2.4.5 VMT Thresholds
The CEQA Guidelines encourage local jurisdictions to adopt significance thresholds intended for general
use by resolution or ordinance as part of a public process. Lead agencies also have the option to establish
thresholds on a project-by-project basis. Adopting these thresholds through a public process improves
transparency and can be used to help educate the public and project applicants about the City’s
expectations. The City of Petaluma has two primary options for setting a VMT threshold for land use
projects and plans: adopt a threshold recommended by another public agency or adopt a jurisdiction-
specific VMT threshold.
The State’s guidance on thresholds is presented in the OPR Technical Advisory and the ARB California Air
Resources Board 2017 Scoping Plan – Identified VMT Reductions and Relationship to State Climate Goals.
The OPR threshold generally requires land use projects to achieve a VMT reduction of 15 percent below
the city or regional (i.e. nine-county Bay Area) baseline average depending on the type of land use. The
ARB analysis indicates that the VMT threshold would need to be 16.8 percent for automobile only VMT to
achieve state GHG reduction goals. These points of reference are subject to change over time, however,
depending on statewide forecasts of population and travel, as well as economic conditions (e.g. short-
term and long-term effects of the COVID-19 pandemic).
Specific OPR guidance for individual land uses is as follows:
• Residential projects – A proposed project exceeding a level of 15 percent below existing (baseline)
home-based VMT per resident may indicate a significant transportation impact. Existing home-
based VMT per resident may be measured as regional or citywide home-based VMT per resident.
• Office projects – A proposed project exceeding a level of 15 percent below existing (baseline)
regional home-based work VMT per employee may indicate a significant transportation impact.
• Retail projects – A net increase in total VMT may indicate a significant transportation impact. This
metric reflects the nature of most local-serving retail to distribute existing vehicle trips, rather
than generate or induce new vehicle trips.
• Mixed-use projects – Lead agencies can evaluate each component of a mixed-use project
independently and apply the significance threshold for each project type included (e.g., residential
and office). In the analysis of each use, a project should take credit for internal capture.
• Other project types – Lead agencies, using more location-specific information, may develop their
own more specific thresholds, which may include other land use types.
• Redevelopment projects – Where a project replaces existing VMT-generating land uses, if the
replacement leads to a net overall decrease in VMT, the project would cause a less than
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significant VMT impact. If the project leads to a net overall increase in VMT, then the thresholds
described above should apply.
While OPR generally recommends a threshold at 15 percent below baseline levels for residential and
office projects, OPR also recommends that any increase in VMT from a retail project be treated as
significant. Further, ARB recommends a VMT reduction of 16.8 percent below 2018 levels (for automobile-
only VMT) for new development to contribute its fair share to meeting state emissions reduction goals.
The ARB threshold is supported by substantial evidence given its direct connection to emissions goals and
forecasts.
A key consideration for Petaluma is that the city’s current VMT rates for residents and employees are
higher than the regional average (Table 1 below), and accomplishing a 15.0 or 16.8 percent reduction
(when comparing cumulative VMT for projects to the existing Bay Area VMT average) would require
mitigation strategies not previously attempted.
A potential challenge to any VMT threshold is the ARB SB 150 report (2017), which includes evidence that
VMT per capita is increasing and, as a result, so are GHG per capita emissions. Furthermore, the thresholds
published by ARB and OPR are based on a number of assumptions about future outcomes related to VMT
generation of current residents, fuels, electric vehicles, that may not qualify as reasonably foreseeable
under CEQA and do not consider the influence of transportation network companies (e.g., Uber and Lyft)
and autonomous vehicles (AV) on travel behavior. These sorts of travel trends, if they continue, may
contribute to ‘other substantial evidence’ that must be considered and discussed when making a
significance finding. It is noted, however, that the ARB SB 150 report analyzed VMT per capita before the
COVID-19 pandemic, and the quantified effects of the pandemic on VMT per capita is unknown at this
time.
Caltrans released a draft VMT-Focused Transportation Impact Study Guide (February 28, 2020) that
recommends use of the OPR thresholds for land use projects and plans. This guidance did not specify
whether to use the 15.0 or 16.8 percent threshold value (both values are included in the OPR Technical
Advisory). The Caltrans Guide also mentions that Caltrans may request additional analysis for
transportation projects; standards for those projects are discussed below.
OPR and Caltrans recommend that a net increase in total VMT may indicate a significant impact for
transportation projects. Why transportation projects should be treated differently than land use projects is
not disclosed or supported by substantial evidence. A net decrease or no change in VMT would be
evidence of a less than significant VMT impact.
Projects that reduce or have no impact on VMT include most active transportation projects, road diets,
and minor operational changes to local roadways. However, capacity increases (i.e., lane additions) on
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arterial roadways or roadways that carry regional traffic have the potential to induce new vehicle traffic,
and therefore new VMT. As an example, adding an additional lane on an arterial roadway that reduces
delay, may make driving even more competitive than walking, and shift some trips to from walking to
driving.
The no net new VMT threshold is the threshold preferred by Caltrans for assessment of impacts to
Caltrans facilities and recommended in the OPR Technical Advisory. As a threshold, it is also reflective of
whether a project simply improves operations for existing users (decreasing delay or improving safety
with no change in VMT) or if it also induces demand for driving.
2.4.6 Screening Criteria
The OPR Technical Advisory includes suggested methods for screening projects to quickly identify when a
project should be expected to cause a less than significant VMT impact for the CEQA Transportation
section without conducting a detailed VMT analysis. The OPR Technical Advisory suggests that lead
agencies may screen out VMT impacts for small projects, residential and office projects located in low-
VMT areas (as per the SCTA travel demand model or other sources of VMT), projects located in proximity
to a major transit stop (per specific definitions in the OPR Technical Advisory), affordable housing
developments, and transportation projects that would not result in an increase to vehicle capacity. Since
land use plans affect a larger area and serve as the basis for environmental analysis of future projects, all
land use plans (including the General Plan, Precise Plans, and Specific Plans) should conduct a quantitative
VMT analysis and not utilize screening, unless they can be screened out due to proximity to major transit.
2.4.7 Mitigating VMT Impacts
Mitigation strategies related to reducing VMT impacts to less-than-significant levels are related to
reducing the number and distance of vehicle trips generated by a particular project. This is in contrast to
mitigation under congestion-based metrics such as LOS, whereby congestion impacts are mitigated
through adding capacity; in some cases, these capacity improvements induce driving, and thus lead to
more VMT being generated.
VMT impact mitigation strategies generally take the form of Transportation Demand Management (TDM)
measures. TDM measures include strategies related to parking, transit usage, encouraging a mix of land
uses on site, and promoting the use of active transportation and higher-occupancy vehicle models (e.g.
carpooling and transit). TDM can be applied on a project-by-project basis, or as part of a citywide TDM
program. Until a citywide program is established, most projects requiring mitigation would apply TDM
strategies on a project-by-project basis.
A key part in the CEQA process is the demonstration of the effectiveness of the selected mitigation
strategies. For example, under congestion-based analyses, one could demonstrate the effectiveness of
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adding capacity by re-running the traffic operations model with the added capacity to determine the
reduction in congestion after implementation of the improvement. Because the amount of research on
the effectiveness of TDM strategies is limited (i.e. CAPCOA’s Quantifying Greenhouse Gas Mitigation
Measures publication), demonstrating the VMT reduction effectiveness of project-by-project TDM
measures to the standard required by CEQA may be difficult. For example, the effectiveness research in
the CAPCOA document is limited in its scope and breadth of research site locations and contexts; thus, in
some cases, the research in the CAPCOA document may not be relevant to projects in Petaluma.
Additionally, as noted in the CAPCOA document, the research suggests that there is a maximum potential
effectiveness associated with implementing all feasible TDM strategies; for suburban contexts like
Petaluma, this maximum potential effectiveness is 15 percent. As VMT effectiveness in Petaluma is
monitored and evaluated, empirical data may support different, locally-specific conclusions relative to the
CAPCOA research.
Citywide TDM strategies and fee programs may allow developers to mitigate land use project impacts
through funding of strategies that will reduce VMT generated by the project as well as other existing land
uses throughout the City. One such example of an in-lieu fee program includes San Diego’s Complete
Communities Initiative, which is described below.
Case Study – San Diego’s Complete Communities: Housing Solutions and Mobility Choices Initiative
San Diego’s proposed Complete Communities initiative aims to “connect every San Diegan with safe and
convenient mobility choices to jobs, open spaces, shopping, services, neighborhood parks, and other
amenities5.” The program seeks to reduce VMT created by new development in more urban
neighborhoods by requiring on-site or site-adjacent VMT reducing amenities and programs while
development occurring in non-urban areas would be required to pay an in-lieu fee6 that would be used to
construct transit, bicycle, and pedestrian infrastructure in more urban areas of the City. Development in
non-urban areas would result in the greatest VMT generation; however, VMT reducing amenities in non-
urban areas are least effective as they are characterized by being farther away from jobs, services, and
shopping (making bicycling and walking difficult) and limited access to transit. This program applies to
ministerial and discretionary projects to comprehensively reduce citywide VMT and provides a mechanism
5 For more information on San Diego’s program, visit: https://www.sandiego.gov/planning/programs/mobility/mobilitychoices 6 An in-lieu fee program requires a ‘reasonable relationship between the ordinance and enhancement of public welfare’ per decisions such as California Building Industry Assn. v. City of San Jose (2015) 61 Cal.4th 435 (CBIA) to establish the nexus for the in-lieu fee. A reasonable relationship could be established by demonstrating that new development increases citywide VMT and the VMT reduction ordinance amenities and construction transit, bicycle, and pedestrian infrastructure reduce citywide VMT.
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for mitigation to address development project VMT impacts that is predictable; however, it does not
replace or offset the City’s traffic impact fee program.
Chapter 4 of this report includes a more detailed discussion of potential TDM strategies that could be
implemented in Petaluma. Section 3.5 presents TAC recommendations for mitigating VMT impacts in the
City of Petaluma as well as recommendations for associated next steps to bolster mitigation options for
future projects in the City.
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3. Implementation Recommendations
This chapter includes recommendations for VMT metrics, methods, thresholds, screening criteria and
mitigation options for the City of Petaluma. The recommendations are based on feedback from the TAC
formed for the purposes of SB 743 implementation in the City of Petaluma.
3.1 Metrics
As noted in Section 2.4.1, a variety of VMT metrics were submitted to the TAC for their review and
feedback. Topics for discussion amongst TAC members included consistency with the OPR Technical
Advisory, a desire for the metrics to capture a wide range of VMT, and the ability of travel demand models
to calculate the metrics.
Technical Advisory Committee Recommendation for VMT Metrics
The TAC discussed how various metrics would more fully capture VMT generated by, and interactions
between, various land uses within the City (e.g. residential, office, retail, schools, commercial services, etc.),
how the metrics could promote a more sustainable transportation future for the City that encourages
walking, bicycling and transit uses between destinations, the ability of travel demand models to calculate
the metrics, and the desirability of consistency with the OPR Technical Advisory. Based on the desire to
find balance amongst these factors, the TAC has recommended the following VMT metrics for adoption
by the City of Petaluma:
• Residential projects: total home-based VMT per resident
• Office and other employment-focused projects: total home-based work VMT per employee
• Retail and other commercial service projects: total project effect on VMT within a geographic
area
3.2 Methods
As noted in Section 2.4.2, three candidate travel demand models were submitted to the TAC for review
and feedback. Topics for discussion amongst the TAC members included the level of detail of each model,
the schedule of previous/future updates to model data, and the ability of the model to precisely analyze
developments that are typical for the City of Petaluma (with respect to project type and scale).
Technical Advisory Committee Recommendation for VMT Methods
The TAC received a presentation from Chris Barney, Senior Transportation Planner at SCTA and SCTA’s
lead travel demand modeler on the capabilities of the updated SCTA model. He noted that the model
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provides better detail on land uses in Sonoma County as well as a robust transportation system for which
trips are routed upon; these details are key in the more precise estimate of VMT. The TAC discussed the
need to use a travel demand model (as suggested by OPR in the Technical Advisory), the detail included in
the three reviewed modeling options, the ease of use of each model, and the data update/model
maintenance schedule for each model. Based on discussions amongst TAC members about these factors,
the SCTA travel demand model is recommended for use in the calculation of VMT for projects in the City
of Petaluma.
3.3 Thresholds of Significance
As noted in Section 2.4.5, a number of options for thresholds of significance exist. Thresholds should be
based on substantial evidence per the CEQA Guidelines, and thresholds may be based on substantial
evidence developed by other agencies. The TAC was presented with threshold options including the 15-
percent and 16.8-percent thresholds recommended by OPR and ARB, respectively. TAC members
discussed how the thresholds would consider the City’s climate emergency declaration, commitment to
sustainability and resiliency, need to address the housing crisis, and other factors contributing to VMT that
are outside of the City’s control (e.g. the City’s location in the region relative to other areas of
employment, retail and housing).
Technical Advisory Committee Recommendation for VMT Thresholds
Based on these discussions, the TAC recommended that the City of Petaluma adopt the following
thresholds that identify a significant impact with respect to VMT:
A project would result in a significant impact and require mitigation if:
• For residential projects: Project total home-based VMT per resident exceeds 16.8% of the citywide average. The citywide average baseline value applies until such time that the City of
Petaluma exceeds the housing allocation for the City as identified in the Sustainable Communities
Strategy (SCS) for the Bay Area region; if the City exceeds the SCS housing allocation, the nine-county Bay Area regional average applies7.
• For office and other employment-focused projects: Project total home-based work VMT per
employee exceeds 16.8% of the nine-county Bay Area regional average.
• For retail and other commercial service projects: Project results in a net increase in VMT over
the geographic area that the project influences.
7 The SCS housing allocation limit is suggested by the California State Office of Planning and Research (OPR) in the Technical Advisory on Evaluating Transportation Impacts in CEQA as when the use of a citywide average becomes inappropriate for the evaluation of CEQA VMT impacts (in favor of the Bay Area regional average).
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• For mixed-use and other projects: Project components should be analyzed using the relevant
thresholds for residential, office/employment-focus, or retail/commercial service projects. The
benefit of a mix of uses on-site can and should be included in the analysis.
• For transportation projects: Project results in induced travel and an increase in citywide VMT.
• For redevelopment projects: Project results in increased VMT versus current land uses. City staff
retain discretion to identify the baseline VMT for use in the calculation (i.e. based on current uses or permitted uses).
Further, the TAC recommended that the City conduct a review of these thresholds of significance after
completing the City of Petaluma’s Climate Action Plan and General Plan Update to ensure they are
consistent with the City’s goals for reducing greenhouse gas and VMT. If the above thresholds are not
consistent with these goals, then the City shall update the thresholds to ensure alignment.
3.4 Screening Criteria
It is generally recommended that the City use the screening criteria presented in the OPR Technical
Advisory, with minor modifications or exclusions. The TAC was presented with the Technical Advisory
screening criteria, and generally recommended their adoption, with some minor modifications (e.g.
limiting exemptions for projects with drive-throughs), as described below. A VMT analysis may still be
required to provide inputs for the Air Quality, Greenhouse Gas and Energy CEQA analyses; this analysis
could be completed using the SCTA travel demand model or other VMT evaluation tools (e.g. CalEEMOD).
Technical Advisory Committee Recommendation for VMT Screening Criteria:
Screening for Small Projects
The TAC has recommended that the City screen projects that generate or attract fewer than 110 trips per
day. Based on research for small project triggers8, this may equate to nonresidential (e.g., office) projects
of 10,000 square feet or less and residential projects of 15 units or less. The City of Petaluma may also
screen local-serving retail projects (projects with less than 30,000 square feet of retail) on the basis that
they attract trips that would otherwise travel longer distances. Projects with drive-throughs would be
excluded from screening under these criteria, and City staff retain discretion to deny the use of the small
project exemption if substantial evidence exists that screening is not appropriate.
Screening for Projects Located in Low-VMT Areas
The TAC has recommended that the City screen residential and office projects located in low-VMT areas
(per the CEQA thresholds to be established by the City) that incorporate similar features to the nearby
8 Refer to technical memorandum on small project triggers in Attachment A.
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developments (i.e., density, mix of uses, and transit accessibility) on the basis that the project will exhibit
similarly low VMT. Typically, this screening is performed by utilizing data from a travel demand model (e.g.
the SCTA travel demand model) and comparing the project’s characteristics to land uses currently in the
low-VMT area. If the project is inconsistent with the underlying data (e.g., a single-family project in a zone
with no existing single-family residential uses), then screening is not appropriate and a detailed VMT
analysis should be conducted to determine whether the project exceeds the VMT. Projects with drive-
throughs would be excluded from screening under these criteria, and City staff retain discretion to deny
the use of the low-VMT area exemption if substantial evidence exists that screening is not appropriate.
Screening for Projects in Proximity to a Major Transit Stop
The TAC has recommended that the City screen projects that are located within a half mile of an existing
or planned high-quality transit corridor or major transit station. Proximity to transit is explicitly listed in
the CEQA Guidelines as a reason to presume a project has no significant impacts based on VMT. In
Petaluma, this includes the existing Downtown Petaluma SMART station, the planned Petaluma North
SMART station (also known as the Corona Station), and at stops for bus routes with 15 minute or less
headways.
The OPR Technical Advisory notes that a presumption of less than significant should not be applied, and a
VMT analysis should be performed, if the project:
• Has a Floor Area Ratio (FAR) of less than 0.75
• Includes more parking than required by the City of Petaluma
• Is inconsistent with Plan Bay Area
• Replaces affordable residential units with a smaller number of moderate- or high-income
residential units (although a small market-rate project could qualify for small project screening)
If any of the above conditions apply, a detailed VMT analysis should be conducted to determine whether
the project exceeds the VMT thresholds. Projects with drive-throughs would be excluded from screening
under these criteria, and City staff retain discretion to deny the use of the proximity to major transit stop
exemption if substantial evidence exists that screening is not appropriate.
Screening for Affordable Housing
The TAC has recommended that the City screen residential projects containing 100 percent affordable
housing (based on local circumstances and substantial evidence as determined by the City) on the basis
that affordable housing generates less VMT than market-rate housing. Furthermore, affordable housing
located within infill locations generally improves jobs-housing balance and may thus result in shorter
commutes for low-income workers.
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Screening for Transportation Projects
The TAC has recommended that the City screen transit projects, bicycle and pedestrian projects, and
roadway maintenance projects that do not result in an increase in vehicle capacity or VMT. Refer to pages
20 and 21 of the Technical Advisory for a complete list of transportation projects that may be screened
out from a VMT analysis.
3.5 Mitigation Options
As noted in Section 2.4.7, project VMT in exceedance of thresholds of significance require that a project
implement mitigation measures to reduce the number of project trips generated and/or reduce the length
of project-generated trips. The TAC was provided with information regarding how mitigation measures
may be applied on a project-by-project basis, how citywide TDM programs could be developed whereby
projects could pay into an in-lieu fee program to fund the citywide TDM program, and how projects could
take advantage of mitigation bank programs that may be developed in the future.
Technical Advisory Committee Recommendation for Mitigating VMT Impacts:
The TAC recommended the following near-term, medium-term and far-term strategies:
• Near-Term: The TAC has recommended that mitigation be performed on a project-by-project
basis using available TDM effectiveness research as a guide to demonstrate the effectiveness of mitigation strategies. TDM strategies related to promoting transit usage, active transportation,
and more sustainable parking strategies should be prioritized.
• Medium-Term: The TAC has recommended that the City investigate and implement citywide TDM programs and fund these programs through developer fees.
• Far-Term: The TAC has recommended that the City coordinate with SCTA and other agencies in
Sonoma County to develop a VMT mitigation banking program, should pilot programs in Contra Costa County and Southern California prove successful.
Chapter 4 provides more information on near-term, project-by-project TDM strategies for use in
mitigating land use projects until citywide or County-wide mitigation strategies can be established.
3.6 CEQA VMT Transportation Impact Analysis Guidelines
Fehr & Peers has developed guidelines for the study of a project’s transportation impacts using VMT as
the CEQA Transportation section metric. These guidelines are provided in Appendix B, and provide
information on general VMT methodology, thresholds of significance and mitigation strategies; a
flowchart of the process of determining if a traffic study is needed is presented on Figure 2. These
guidelines are anticipated to evolve over time as (1) more data becomes available, (2) the City takes
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additional steps to implement VMT and mitigation measures in the City, and (3) as a body of CEQA case
law develops around the topic of VMT analysis for CEQA Transportation purposes.
3.7 Disruptive Trend Impacts on VMT Estimation
The VMT methodologies and thresholds described above are based on a presumption that future travel
behavior will be consistent with recent travel behavior. Disruptive trend changes including current COVID-
19 effects, TNCs such as Uber and Lyft, lower fuel prices, and public availability of AVs may change future
travel behaviors, resulting in future VMT differing from current forecasts. As these trends evolve, models
will need to be updated to reflect them. Generally, the SCTA travel demand model is updated on a five-
year update schedule; the City of Petaluma, as one of SCTA’s member agencies, could request a
supplemental update once the effects of COVID-19, related economic effects, and other disruptive trends
become more known and quantified.
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Figure 2: Transportation CEQA Process
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4. TDM Strategy Research
This chapter summarizes an assessment of new research related to transportation demand management
(TDM) effectiveness for reducing VMT. The purpose of this work was to compile new TDM information
that has been published in research papers since release of the Quantifying Greenhouse Gas Mitigation
Measures (CAPCOA, August 2010) and to identify those strategies suited to Petaluma given its suburban
land use context. This information has informed the development of a menu of mitigation options that are
applicable for potential use in Petaluma, as outlined on Figure 3.
An important consideration for the effectiveness of these VMT reduction strategies is the appropriate
scale of implementation. The strategies described in this section include programmatic strategies (e.g.,
VMT impact fee programs, VMT exchanges, and VMT banks), city-scale transportation infrastructure
strategies (e.g., expanding the transit or bicycle network), and project-level strategies (e.g., building site
transportation demand management [TDM] strategies such as parking pricing and transit pass subsidies).
The largest reductions in VMT (and resulting emissions) derive from regional policies related to land use
location efficiency and infrastructure investments that support transit, walking, and biking. While there
are many measures related to site design and building operations that can influence VMT and emissions,
these measures typically have smaller effects on VMT reduction and are often dependent on the travel
behavior of residents/tenants.
To caveat the information presented in this section, the existing tools and methods for quantifying VMT
reduction are prone to a high margin of error due to limited data and research on this topic as a result of
recent regulatory changes (i.e., SB 743 and the policy change from LOS to VMT) as well as challenges in
understanding the complex factors that influence travel behavior. To some degree, this is consistent with
uncertainty that exists with previously acceptable CEQA transportation practices, such as calculations of
Level of Service (LOS) based on forecasted intersection volumes. However, unlike LOS, monitoring of
TDM effectiveness would be required at the project level as a condition of approval for discretionary
projects. The ultimate strategies adopted for VMT reduction should be refined as additional research on
the topic of VMT reduction becomes available and, as with all CEQA practice, based on substantial
evidence.
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Figure 3: Menu of VMT Options
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4.1 Recommended VMT Reduction Strategies
Of the strategies included in the tools and research described above, only a few strategies are likely to be
effective in a suburban setting such as Petaluma. With Petaluma’s land use context in mind, each
strategy’s effectiveness was considered and nine were selected for detailed review. Strategies 1, 2, 3, and
4 present project-level mitigation, while strategies 5, 6, 7, 8 and 9 present community-level mitigation.
Individual development projects have limited ability to implement community-level strategies, but may be
able to contribute to established community-level strategies. It is noted that disruptive trends, including
but not limited to, transportation network companies (TNCs such as Uber and Lyft), autonomous vehicles
(AVs), internet shopping, and micro-transit (e.g., electric scooters) may affect the future effectiveness of
these strategies.
4.1.1 Project/Site Level Strategies
1. Increase diversity of land uses – This strategy focuses on inclusion of mixed uses within projects
or in consideration of the surrounding area to minimize vehicle travel in terms of both the
number of trips and the length of those trips. Typical applications of a mix of uses include
ground-floor retail at larger residential developments or the construction of live-work units. This
strategy may not be feasible for smaller projects or projects subject to limited uses due to zoning
such as single-family residential uses.
2. Increase density – This strategy focuses on increasing residential density within projects, which is
associated with lower VMT per capita. Increased residential density in areas with high jobs access
may have a greater VMT change than increases in regions with lower jobs access. The provision of
Auxiliary Dwelling Units (ADUs) may reduce VMT per capita, depending on their use and person-
occupancy. This measure also applies at the city and community level, with neighborhoods of
higher density typically having lower VMT per capita.
3. Increase transit accessibility – This strategy focuses on ensuring site design favors access to
existing or planned transit stations and is commonly referred to as Transit-Oriented Development
(TOD). This strategy includes maximizing the amount of developable space within walking
distance to transit stations (typically considered a radius of ¼ to ½ mile of a transit station),
and/or deemphasizing automobile facilities such as vehicle parking, garages, and driveways.
4. Encourage telecommuting – This strategy relies on effective internet access/speeds, flex space,
and/or accessory office units for individual project sites/buildings that provide the opportunity for
telecommuting. The effectiveness of the strategy depends on the ultimate building tenants; this
should be a factor in considering the potential VMT reduction, as tenants may change over time.
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4.1.2 City/Community Level Strategies
5. Provide pedestrian network improvements – This strategy focuses on creating a pedestrian
network and connecting projects to nearby destinations via pedestrian pathways. Projects in the
City of Petaluma range in size, so the emphasis of this strategy for smaller projects would likely be
the construction of network improvements that connect the project sites directly to nearby
destinations. For larger projects, this strategy could focus on the development of a robust
pedestrian network within the project itself. Alternatively, implementation could occur through an
impact fee program or benefit/assessment district based on local or regional plans.
6. Provide traffic calming measures and low-stress bicycle network improvements – This strategy
combines the CAPCOA research focused on traffic calming to provide a low-stress bicycle
network. Traffic calming creates networks with low vehicle speeds and volumes that are more
conducive to walking and bicycling. Implementation options are similar to those for providing
pedestrian network improvements. One potential change in this strategy over time is that e-bikes
(and e-scooters) could extend the effective range of travel on the bicycle network, which could
enhance the effectiveness of this strategy.
7. Implement market price public parking (on-street) – This strategy focuses on implementing a
market-based pricing strategy for on-street parking within central business districts, employment
centers, and retail centers to encourage “park once" behavior. This measure deters parking
spillover from project supplied parking to other public parking nearby, which undermine the
vehicle miles traveled (VMT) benefits of project pricing. It may also generate sufficient area-wide
mode shifts to justify increased transit service to the area.
8. Increase transit service frequency and speed – This strategy focuses on improving transit service
convenience and travel time competitiveness with driving. While the City of Petaluma has fixed
route rail and bus service that could be enhanced, it is possible that new forms of low-cost,
demand-responsive transit service could be provided. Given land use density in Petaluma, this
strategy may be limited to traditional commuter transit where trips can be pooled at the start and
end locations or require new forms of demand-responsive transit service. The demand-responsive
service could be provided as subsidized trips by contracting to private transportation network
companies (TNCs) or Taxi companies. Alternatively, a public transit operator could provide the
subsidized service but would need to improve on traditional cost effectiveness by relying on TNC
ride-hailing technology, using smaller vehicles sized to demand, and flexible driver employment
terms where drivers are paid by trip versus by hour. Note that implementation of this strategy
would require regional or local agency implementation, substantial changes to current transit
practices, and would not likely be applicable for individual development projects. Additionally,
this strategy is only effective in VMT reduction if it includes a pooling element to increase average
vehicle occupancy.
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9. Implement a car and micro-mobility (bike or scooter) sharing program – This strategy reduces the
need to own a vehicle or reduces the number of vehicles owned by a household by making it
convenient to access a shared vehicle for those trips where vehicle use is essential. Bicycle and
scooter sharing programs provide convenient connections for short-trips that do not require a
car. Note that implementation of this strategy would require regional or local agency
implementation and coordination and would not likely be applicable for individual development
projects, although individual projects and provide parking and supportive services to these
programs.
The VMT reduction strategies can be quantified using CAPCOA calculation methodologies, recent ARB
research findings, or SANDAG’s VMT calculator. Appendix C provides calculation methodologies for each
of the mitigations provided above, along with their range of effectiveness.
Additional VMT reduction strategies that are not quantified in this section but may be considered for future implementation in Petaluma include:
• Engagement with bicycle advocacy groups such as the League of American Bicyclists to work
towards certification as a bicycle friendly community
• Implement education strategies to inform the public about the Vision Zero strategies to improve
road safety, increase health outcomes from active transportation, and decrease VMT
• Add additional wayfinding signage and safety procedures for bicycling through Downtown
• Incentivize non-vehicular tourism in Petaluma through partnerships with SMART and upcoming
Bike Share providers as well as providing protected bicycle routes for tourists to major
destinations, such as between SMART and Downtown
• Improve Petaluma’s existing dirt trails to accommodate wider range of bicyclists
• Incentivize active transportation through market pricing strategies with employers, stores, and
public transit9
• Collaborate with TNCs to provide first mile/last mile connections to high frequency transit
corridors. Transit timing, carpooling, and ride discounts associated with TNC partnerships should
be considered as simultaneous strategies, following the lead of other cities implementing such
programs.
9 The Dutch government pays workers 22 cents for every kilometer they pedal, reported by Huffington Post. https://www.huffpost.com/entry/netherlands-pays-bike-work-commute_n_5c6dc15ae4b0e2f4d8a23e3e
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4.2 Combining VMT Reduction Strategies
Each of the TDM measures described previously can be combined with others to increase the
effectiveness of VMT mitigation; however, the interaction between the various TDM measures is complex
and sometimes counterintuitive. Generally, with each additional measure implemented, a VMT reduction
is achieved, but the incremental benefit of VMT reduction may diminish. To quantify the VMT reduction
that results from combining TDM measures, the formula below can be applied absent additional
information: 𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 𝑉𝑉𝑉𝑉𝑇𝑇 𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑇𝑇𝑅𝑅𝑇𝑇𝑅𝑅=(1 − 𝑃𝑃𝑎𝑎)∗(1 − 𝑃𝑃𝑏𝑏)∗(1 − 𝑃𝑃𝑐𝑐)∗…
Where: 𝑃𝑃𝑥𝑥 = percent reduction of each VMT reduction strategy
This adjustment methodology is a mathematical approach to dampening the potential effectiveness and
is not supported by research related to the actual effectiveness of combined TDM strategies. The intent
of including this formula is to provide a mechanism for dampening to minimize the potential to overstate
the VMT reduction effectiveness.
Another important consideration when combining TDM measures is whether a maximum VMT reduction
should be applied based on the land use context. The CAPCOA methodology identifies VMT reduction
maximums based on community types tied to land use context. The caps are applied at each step of the
VMT reduction calculation (i.e., at the strategy scale, the combined strategy scale, and the global scale).
However, these caps are not based on research related to the effectiveness of VMT reduction strategies in
different land use contexts. The cap differences are largely based on VMT generation differences within
different land use contexts and serves as a proxy for potential limits on VMT reduction strategy
effectiveness. For suburban jurisdictions such as Petaluma, CAPCOA identifies a global VMT reduction
maximum of 15 percent, although 20 percent may be feasible in suburban center locations, such as
locations in transit-oriented and downtown Petaluma. For more information on VMT reduction
maximums, see Appendix D, which contains an excerpt from the CAPCOA report describing the
calculation of combined VMT reduction strategies.
As noted previously, additional data is needed to support and refine the above approach for quantifying
the effects of combining VMT reduction strategies. Analysts should consider the available substantial
evidence at the time a study is prepared and provide justification to support the effectiveness of TDM
measures in order to inform CEQA review. We recommend conducting additional research into the
effects of combining VMT reduction strategies, which may include the collection of measurable data from
within Petaluma or cities of similar size and land use context, and summarizing the database for use in
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developing the justification for the effectiveness of mitigation measures (including supporting a finding of
effectiveness beyond the 15 percent maximum reduction suggested in the CAPCOA guidance).
4.3 Implementing VMT Reduction Strategies
Project or site-level VMT reduction strategies often involve increasing land use density, changing the mix
of uses, or altering the transportation network. However, a potential limitation of these physical design
changes is that they may result in a project that no longer resembles the original applicant submittal.
CEQA is intended to disclose the potential impacts of a project and mitigate those impacts but has
limitations with regards to using mitigation to fundamentally change the project. Therefore, these
strategies may result in an inconsistency with the project description when applied on an ad hoc basis.
Another common strategy is to add a TDM program to the project as a condition of approval. While
evidence exists that TDM programs can reduce VMT, their success depends on the performance of future
building tenants that can change over time. Hence, an effective TDM mitigation program will often
require ongoing monitoring and adjustment to ensure long-term VMT reduction is achieved. The cost to
provide this monitoring may not be feasible for all projects.
In response to the limitations of focusing exclusively on site-level TDM strategies, new mitigation
concepts are emerging that cover larger areas and rely on citywide programs to achieve VMT reductions.
These mitigation concepts (or programs) are outlined below. As with all VMT mitigation, these programs
require substantial evidence to document that the projects included in the programs would achieve the
expected VMT reductions. Additionally, the discretionary action to adopt the program may require CEQA
review.
1. VMT Impact Fee Program – This concept resembles a traditional impact fee program in
compliance with the mitigation fee act and uses VMT as a metric. The nexus for the fee program
would be a VMT reduction goal consistent with the CEQA threshold established by a lead agency
for SB 743 purposes. The main difference from a fee program based on a metric such as vehicle
LOS is that the VMT reduction nexus results in a capital improvement program (CIP) consisting
largely of transit, bicycle, and pedestrian projects. These types of fee programs are time
consuming to develop, monitor, and maintain but are recognized as an acceptable form of CEQA
mitigation if they can demonstrate that the CIP projects will be fully funded and implemented.
The City of Los Angeles is the first city in California to complete a nexus study for this type of
program.
2. VMT Exchanges – This concept (along with VMT banks) borrows mitigation approaches from
other environmental analysis such as wetlands. The concept relies on a developer agreement to
implement a predetermined VMT-reducing project in exchange for the ability to develop a VMT-
generating project. The projects may or may not be located near each other. The concept
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requires a facilitating entity (such as the lead agency) to match the VMT generator (the
development project) with the VMT-reducing project and ensure through substantial evidence
that the VMT reduction is valid (i.e., the VMT reduction is caused by the mitigation and would not
occur otherwise; this concept is known as additionality). VMT Exchanges also require a
determination of the necessary time period to demonstrate a VMT reduction.
3. VMT Banks – This concept attempts to create a monetary value for VMT reduction (e.g., credits)
that can be exchanged amongst individual projects. This program is more complicated than a
simple exchange and would require more time and effort to set up and implement. Another key
challenge of this program is determining how much VMT reduction is associated with each credit.
Similar to VMT exchanges, this mitigation program must also demonstrate additionality.
Table 4 compares the pros and cons of the above programs. As seen in Table 4, all of the program
options have challenges.
Table 4: Comparison of Programmatic VMT Reduction Strategies
Program Structure Pros Cons
Impact Fee Program
• Common practice
• Accepted for CEQA mitigation
• Adds certainty to development costs
• Allows for regional scale projects
• Time consuming and expensive to develop and maintain
• Requires strong nexus
Mitigation Exchange • Limited complexity
• Reduced nexus obligation
• Requires additionality
• Mismatch between mitigation need and mitigation projects
• Unknown timeframe for mitigation life
Mitigation Bank • Adds certainty to development costs
• Allows for regional scale projects
• Allows regional or state transfers
• Requires additionality
• Time consuming and expensive to develop and maintain
• Requires strong nexus
• Political difficulty distributing mitigation dollars/projects
Although implementation of these programs would require an upfront cost, they have several advantages
over site-level TDM strategies:
• CEQA streamlining – These programs provide a funding mechanism for project mitigation and
require significantly less monitoring to demonstrate that significant impacts are reduced to a less-
than-significant level. Additionally, projects could be screened from completing a quantitative
VMT analysis; or, if a quantitative VMT analysis is required, the cost would be somewhat less than
the cost for analyzing LOS impacts.
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• Greater VMT reduction potential – Since these programs coordinate citywide land use and
transportation projects, they have the potential to result in greater VMT reduction potential than
site-level TDM strategies applied on an ad hoc basis. Additionally, these programs expand the
amount of feasible mitigation for reducing VMT impacts.
• Legal defensibility – The VMT reduction programs can help build a case for a nexus between a
VMT impact and funding for capital improvement programs.
A General Plan update is a desirable time to identify and implement any preferred VMT reduction
programs as it allows for coordination between land development, capital improvement projects, and
funding programs. It is recommended that a citywide VMT reduction program be developed as part of the
forthcoming General Plan update. These citywide VMT reduction programs have the ability to reduce VMT
associated with existing VMT sources and VMT from new developments, thus promoting achievement of
citywide sustainability goals on the basis of new and existing development.
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5. Considerations for Updating Recommendations
The information in this report is based on the latest research available at the time of publication as well as
feedback and recommendations from TAC members. A number of factors may result in the revision of the
recommendations in this report to reflect the following change factors:
• Updated technical research on VMT evaluation and VMT mitigation effectiveness research
• Updated technical guidance from the State Office of Planning and Research
• Updated City General Plan goals and policies related to the circulation system and environment
• New State-wide environmental legislation
• New court cases and other laws affecting CEQA (per typical CEQA practice)
Barring major court cases or new state laws affecting CEQA VMT analysis, the thresholds and other related
recommendations are anticipated to be valid until the next General Plan update (scheduled to be
concluded in the mid-2020s) and may remain valid after the update. At that time, the recommendations in
this report may be revisited to reflect updates to the City’s General Plan goals and policies; changes may
be adopted by the City Council, if deemed necessary, to implement the City’s update General Plan goals
and policies as part of the General Plan adoption process (including environmental clearance).
Outside of the General Plan update process, the City retains discretion to set CEQA thresholds based on
substantial evidence. If evidence exists that the adopted VMT thresholds, the City Council could choose to
adopt an ordinance or resolution revising the VMT thresholds. The City also has discretion to use CEQA
thresholds on a one-time (i.e. non-general use) basis as long as they are supported by substantial
evidence per CEQA; this approach could be helpful if a new CEQA court ruling affects VMT thresholds or
VMT analysis approaches.
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Appendix A:
Trip Length Adjustments for SB 743
VMT Analysis
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P a g e | 1
Technical Memorandum
Date: November 5, 2019
To: Erik Ruehr, VRPA
Bruce Griesenbeck and Maricela Salazar, SACOG
From: Jimmy Fong, Jinghua Xu, and Ronald T. Milam, Fehr & Peers
Subject: Trip Length Adjustments for SB 743 VMT Analysis
Introduction
SB 743 implementation has created the need to modify travel demand models to ensure they
capture the full trip length for those trips that start or end outside the model boundary. This
need stems from the CEQA guidance listed below and the general desire to avoid arbitrary
truncation of trip lengths based on model or political boundaries.
According to the Technical Advisory, the assessment should cover the full area in which
driving patterns are expected to change, including induced growth impacts and
cumulative impacts. OPR states that the VMT estimation should not be truncated at a
modeling or jurisdictional boundary for convenience of analysis when travel behavior is
substantially affected beyond that boundary. (p. 6 and 23 - Technical Advisory on
Evaluating Transportation Impacts in CEQA, OPR, December 2018)
CEQA Guidelines section 15277:
o “…. Any emissions or discharges that would have a significant effect on the
environment in the State of California are subject to CEQA where a California
public agency has authority over the emissions or discharges.” Since VMT is the
key input for mobile emissions, tracking the full length of trips is essential for
complying with this expectation.
Since all travel demand models in California have boundaries, they truncate trip lengths to varying
degrees. Truncation tends to be most severe at the edge of the model boundary and when the
modeled area exhibits a high proportion of external travel (i.e., from a suburban area in one
region to a job center in another region). To compensate for the influence of model boundaries,
the following steps can be used to modify trip lengths through model gateways.
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Trip Length Adjustment Process
Adjusting the length of trips leaving a model boundary requires appending extra distance at the
model gateway zone (or external centroid) connector as outlined below. This process results in
new gateway distances that are weighted based on the amount and location of external travel
origins and destinations. Other adjustment methods that are available include appending extra
trip lengths to each individual origin-destination (OD) trip pair in the model or expanding the
model’s zone structure to cover a larger area. Both of the methods are much more resource and
time intensive and are not covered further in this memo.
1. Model IX and XI Trips at Gateways
The first step of this process is to determine trip volume leaving or entering the model boundary.
These are referred to in the remainder of this memo as internal-to-external (IX) and external-to-
internal (XI) trips. This data can be generated either from OD trip matrices or by conducting a
select zone analysis to track trips to the model gateways. The volume at the gateways for this
purpose should not include external-to-external (XX) through trips. A table that identifies all
gateways, IX volume, and XI volume should be prepared similar to the example below from the
Mendocino Council of Governments (MCOG) model.
Table 1: Example Model Gateway and IX, XI Link Volumes Table
Gateway ID Gateway Link ID IX Volume XI Volume
7081 SR 1 - South 7081 1,190 1,190
7083 US 101 - South 7083 5,004 5,004
7082 US 101 - North 7082 567 567
7085 SR 20 - East 7085 3,529 3,529
7086 SR 175 - East 7086 551 551
2. Origin-Destination Data between Model and External Areas
Determining the full length of trips leaving or entering a model boundary requires an OD dataset
that includes flows between the model area and the area external to the model. How much of the
external area to include is an important question. Per the CEQA guidance cited, the full length of
trip between their start and end is desired. Whether this extends outside of California has not
been legally tested so it is possible that capturing trip lengths even beyond state limits could be
necessary. An appropriate OD dataset should be chosen based on the details of your project,
context of the study area, level of CEQA risk, and available time and budget for analysis. An
assessment of each of the OD data sources is presented the Table 2.
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Table 2: Origin-Destination Data Assessment
Origin-
Destination
Data Sources
Description Advantages Disadvantages
Available travel
demand model
larger than local
model
All regional models in
California nest within the
California State Travel
Demand Model
(CSTDM).
All local models (i.e., city
models) nest within the
CSTDM and their
respective regional
models.
CSTDM Includes TAZs for the
entire state of California
Regional models are often
the source model for local
model variants, so they have
a high compatibility for
making gateway
adjustments.
CSTDM and regional models
include changes in travel
patterns over time between
base and future years.
Larger models may have
greater aggregation and
only coarse correspondence
between TAZs in the smaller
model.
Regional models may not
fully capture full trip length.
CSTDM has not been
recently calibrated and
validated.
CSTDM truncates trip at
state boundary.
California
Household
Travel Survey
(CHTS)
Survey of California
resident travel that
documents full length of
OD travel.
Robust sample with data
available for most cities and
counties above 50,000
population. Data may be
sufficient for smaller
jurisdictions based on a
review of the sample
Includes all trip purposes.
Insufficient detail below city
level.
2012 data may not reflect
recent changes in travel
patterns.
Does not include data
about future travel.
Longitudinal
Employer-
Household
Dynamics Data
(LEHD)
Employer/Employee
data showing locations
of where employees live
and work, visualized in
an online portal with
export to OD tables,
produced by the U.S.
Census Bureau.
Data available at the census
tract level (or custom TAZ
structure).
2017 data is current.
Quick production of OD data.
Employment data is only
relevant for calculating trip
lengths for home-based
work trips, does not include
other trip purposes.
Does not include data
about future travel.
Mobile device
OD Data
Data from
smartphone/GPS devices
that can be used to
estimate OD trip tables
associated with specific
gateways.
Data available at small scales
(i.e., 250-meter grid cell,
census block group, or
custom traffic analysis zone).
Data scale allows isolation of
specific land uses in many
cases.
2019 data available from
multiple vendors.
Data includes all 365 days of
the year and can be
aggregated.
Limited trip length
truncation.
Includes all trip purposes.
Minimum purchase cost is
about $5000, more
expensive if greater
detail/number of zones is
desired.
Does not include data
about future travel.
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3. Gateway Identification
After identifying an appropriate OD data source, the next step requires determining the
gateway(s) based on the model used in your project, which trips from the OD data source would
travel through. An assessment of options for this process is presented in Table 3.
Table 3: Gateway Identification Methods and Assessment
Data Source Gateway Identification Method
Available travel demand model larger
than local model
A highway skimming procedure to determine the gateway used for
each OD pair for each assignment time period. This method is not
able to track more than one gateway for an OD pair.
A select zone and select link assignment procedure to determine
the gateway(s) for an OD pair. This method requires more
processing/computing time – dependent on the specific travel
model and software.
Mobile Device OD Data Data purchase includes identification of gateway locations and
automatic filtering to create associated OD trip tables.
Streamlined selection with Google
Maps (or online mapping program)
Spreadsheet template that creates a link to Google Maps for each
OD pair, manual identification of gateway(s) in the routing is
required.
An off-model, quick assessment tool, suitable for limited number
of OD pairs.
Not able to quantify the split across multiple routes/gateways (if
applicable) for an OD pair.
Time consuming; not suitable for large number of OD pairs due to
manual process.
4. Weighted Average Trip Length Beyond Model Gateways
The trip length adjustment process ultimately requires calculating the weighted average distance
beyond each model gateway. A list of options for this process is identified in Table 4. Some of
the processes calculate the distance beyond the model gateway directly; while other processes
generate distance between each OD pair first, with a separate calculation for distance beyond the
model gateway.
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Table 4: Trip Length Beyond Model Boundary – Methods and Assessment
Data Source Trip Length Method Description
Available travel demand
model larger than local
model
Creates a new link variable equal to the link length for all the links external to
the local model and 0 for all the links internal to the local model, and then
uses a highway skimming procedure to skim this link variable to generate the
total distance outside of the gateway for each OD pair for each assignment
time period.
Uses a select zone and select link assignment procedure to generate the
volume distribution for each selected gateway, and calculates the weighted
average distance based on the select link volume associated with each
gateway.
CHTS
Estimates total OD distances between origin-destination for each trip record.
Calculates the distance from the trip-end within the model boundary to the
gateway for each record, based on the distance skim from the model, and
subtracts it from the total CHTS OD distance to generate external trip length
for each trip record.
Aggregates the external trip distance across all the trip records to generate
average external trip distance for each gateway.
Mobile Device OD Data
Distance between origins-destinations through each gateway are provided in
the dataset.
Calculates the distance from the trip-end within the model boundary to the
gateway based on the distance skim from the model and subtracts it from
the total mobile device OD distance to generate external trip length for each
gateway.
Streamlined selection with
Google Maps (or online
mapping program)
Links to Google Maps and generates a path for each OD pair.
Calculates the distance between the manually identified gateway(s) and the
trip end location external to the model boundary, based on the shortest
travel time path between the OD pair.
Process Summary
An analyst can mix and match the procedures based on the most appropriate method for each
step. For example, if CHTS is the most appropriate OD dataset to generate external trip length
estimates, the user can generate the OD trip matrices based on CHTS while following the TAZ
structure of the CSTDM, then identify local model gateways in the CSTDM highway network, and
calculate the average trip length beyond each gateway, using the distance skims of the CSTDM,
weighted by trips from the CHTS OD trip matrices.
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Trip Length Adjustment User Guide and Resources
This section provides a user-guide and links to resources for the data sources and processes
previously described in this memorandum.
California Statewide Travel Demand Model (CSTDM)
Caltrans maintains and updates the California Statewide Travel Demand Model, and provides
resources regarding the model on their website:
https://dot.ca.gov/programs/transportation-planning/multi-modal-system-
planning/statewide-modeling
Information regarding the previous version of the CSTDM is no longer available on Caltrans’
website. Caltrans is currently in the process of updating the statewide travel demand model.
Requests regarding statewide modeling should be directed to Caltrans.
An example of the CSTDM used for OD data, gateway selection, and trip length beyond local
model gateways is described below:
Create correspondence between Study Area TAZs within local/regional model to the
Statewide Model TAZs, similar to the example from the Mendocino Council of
Governments (MCOG) Model, as shown in Table 5.
Table 5: Example TAZ Correspondence Table
MCOG TAZ CSTDM TAZ
1 256
3 259
5 259
6 259
7 259
8 260
9 260
10 260
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Add “Gate” attribute to CSTDM roadway network links and set “Gate” equal to gateway id
only for those links identified as the locations corresponding to the local/regional model
gateways.
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Add “Gate_Dist” attribute to CSTDM roadway network links and set “Gate_Dist” equal to
the link distance for those links outside the local/regional model boundary. All the
CSTDM roadway links inside the local/regional model boundary will have a “Gate_Dist”
attribute of 0.
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Run a highway skim on the CSTDM roadway network to skim the shortest travel time
between each OD pair, tracking the gateway and distance outside the local model
boundary. A sample Cube Voyager script for this step is included in the Appendix. An
example output of this process is presented in Table 6.
Table 6: Example OD with Gate Identification and Distance Beyond Local Model
CSTDM
Origin
TAZ
CSTDM
Destination
TAZ
Volume Gateway ID
Distance Beyond
Local Model
Boundary (mi)
246 2 0.21 7082 189.31
246 108 0.1 7082 82.73
246 118 0.42 7082 13.65
246 119 0.29 7082 22.88
246 139 0.13 7085 167.35
246 141 0.07 7085 169.53
246 173 0.25 7082 106.45
246 201 0.07 7085 126.73
For each gateway, summarize the average distance beyond the local model boundary
weighted by volume at each gateway. An example is presented in Table 7.
Table 7: Example Weighted Average Distance Beyond Local Model Boundary
Gateway ID Gateway Weighted Average Distance Beyond Local Model Boundary (mi)
7081 SR 1 - South 28.4
7083 US 101 - South 63.2
7082 US 101 - North 44.7
7085 SR 20 - East 46.4
7086 SR 175 - East 15.9
Tag the gateway distance from the above step using CSTDM to the gateways in the
local/regional model and multiply to the gateway volume from the local/regional model
to determine the gateway external VMT to the local/regional model. Make sure not to
double-count any overlap distance that’s already accounted for in the VMT calculation
from the local/regional model. An example for this calculation for IX trips from the
MCOG model is shown in Table 8.
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Table 8: Example Adjustment Gateway and IX, XI Link Volumes Table
Gateway
Weighted Average Distance
Beyond Local Model Boundary
(From CSTDM)
MCOG IX Volume MCOG IX VMT Beyond
Local Model Boundary
SR 1 - South 28.4 1,190 33,796
US 101 - South 63.2 5,004 316,253
US 101 - North 44.7 567 25,345
SR 20 - East 46.4 3,529 163,746
SR 175 - East 15.9 551 8,761
California Household Travel Survey (CHTS)
CHTS data was collected by Caltrans and is shared on the following website.
https://www.nrel.gov/transportation/secure-transportation-data/tsdc-california-travel-
survey.html
An example of CHTS data filtered for IX trips for Mendocino County is shown below. This
example requires processing of the survey data and specific formatting such that it contains trip
origin, destination, distance, and volume information.
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Longitudinal Employer-Household Dynamics Data (LEHD)
LEHD data can be accessed using the following online resource.
https://onthemap.ces.census.gov/
OD data using this resource can be identified by searching a study area (City, County, or can
upload a shapefile with specific geography) and looking at the “Destination” Analysis Type.
For IX trips, use the “Home” setting for Home/Work Area
For XI trips, use the “Work” setting for Home/Work Area
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Mobile Device OD Data
Streetlight is one vendor that can provide data for OD, gateway identification, and trip lengths. A
middle filter analysis is needed to determine which particular gateway a trip passes through. An
example showing IX trips from Chico to areas beyond the Butte Council of Governments (BCAG)
Model boundary is presented below.
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Google Maps (for Gateway Identification and Trip Length Beyond Local Model
Gateways)
Google Maps (or similar online mapping tool) can be used as a quick tool for gateway
identification and for determining trip lengths beyond a local model boundary. An example of
trips from Chico leaving the BCAG model boundary to Redding is shown below. Trips for this OD
pair pass through the gateway on SR 99 (based on the shortest travel time).
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After a gateway is identified, the distance from the gate location to the trip end outside of the
local model boundary can also be searched, as shown below.
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Appendix (Cube Voyager Sample Script)
;TAZs from local model within the CSTDM
Project1='246-261'
;==================================================
; PM peak period highway skim
RUN PGM=highway
NETI=..\LoadedNetworks\HwyNetwork_Loaded_PM_?.net ; input network
MATO=Skim_PM_?.mat, MO=1-4, NAME=TIME,GATE,GATE_DIST,FULL_DIST ; output skim matrix
PHASE=ILOOP
PATH=LI.TIME_2,MW[1]=PATHTRACE(LI.TIME_2), MW[2]=PATHTRACE(LI.GATE), MW[3]=PATHTRACE(LI.GATE_DIST),
MW[4]=PATHTRACE(LI.DISTANCE)
endphase
ENDRUN
;==================================================
; Summarize OD Volumes and Skim Matrices
RUN PGM=MATRIX
MATI[1]=..\TripTables\OD_?.mat MATI[2]=Skim_PM_?.mat
MATO=OD_Gate_VMT_?.mat, MO=1-6, name=VOL_DAY,GATE,GATE_DIST,GATE_VMT_DAY,FULL_DIST,FULL_VMT
MW[1]=mi.1.1 + mi.1.2 + mi.1.3 + mi.1.4 + mi.1.5 + mi.1.6 + mi.1.7 + mi.1.8 + mi.1.9 + mi.1.10 + mi.1.11 + mi.1.12 + mi.1.13 + mi.1.14 + mi.1.15 + mi.1.16 + mi.1.17 + mi.1.18 + mi.1.19 + mi.1.20 + mi.1.21 + mi.1.22 + mi.1.23 + mi.1.24 +
mi.1.25 + mi.1.26 + mi.1.27 + mi.1.28 + mi.1.29 + mi.1.30 + mi.1.31 + mi.1.32 + mi.1.33 + mi.1.34 + mi.1.35 + mi.1.36 +
mi.1.37 + mi.1.38 + mi.1.39 + mi.1.14 + mi.1.41 + mi.1.42 + mi.1.43 + mi.1.44 + mi.1.45 + mi.1.46 + mi.1.47 + mi.1.48 +
mi.1.49 + mi.1.50 + mi.1.51 + mi.1.52 + mi.1.53 + mi.1.54 + mi.1.55 + mi.1.56 + mi.1.57 + mi.1.58 + mi.1.59 + mi.1.60
MW[2]=mi.2.2
MW[3]=mi.2.3
MW[4]=MW[1]*MW[3]
MW[5]=mi.2.4
MW[6]=MW[1]*MW[5]
ENDRUN
;=========================
; Export to CSV
run pgm=matrix
filei mati[1] = OD_Gate_VMT_?.mat
fileo mato[1]= OD_Gate_VMT_?_IX.csv, MO=1-6, FORMAT=csv, PATTERN=IJM:V, DEC=d, DELIMITER=','
fileo mato[2]= OD_Gate_VMT_?_XI.csv, MO=7-12, FORMAT=csv, PATTERN=IJM:V, DEC=d, DELIMITER=','
IF (I=@Project1@)
MW[1]=MI.1.1 EXCLUDE=@Project1@
MW[2]=MI.1.2 EXCLUDE=@Project1@
MW[3]=MI.1.3 EXCLUDE=@Project1@
MW[4]=MI.1.4 EXCLUDE=@Project1@
MW[5]=MI.1.5 EXCLUDE=@Project1@
MW[6]=MI.1.6 EXCLUDE=@Project1@
ELSE
MW[1]=0
MW[2]=0
MW[3]=0
MW[4]=0
MW[5]=0
MW[6]=0
ENDIF
JLOOP
IF (I=@Project1@ & J=@Project1@)
MW[7]=0
MW[8]=0
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MW[9]=0
MW[10]=0
MW[11]=0
MW[12]=0
ELSEIF (J=@Project1@)
MW[7]=MI.1.1
MW[8]=MI.1.2
MW[9]=MI.1.3
MW[10]=MI.1.4
MW[11]=MI.1.5
MW[12]=MI.1.6
ELSE
MW[7]=0
MW[8]=0
MW[9]=0
MW[10]=0
MW[11]=0
MW[12]=0
ENDIF
ENDJLOOP
ENDRUN
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Appendix B:
CEQA VMT Transportation Impact
Analysis Guidelines
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Draft Memorandum
Date: May 17, 2021
To: Olivia Ervin, City of Petaluma
From: Ian Barnes and Matt Goyne, Fehr & Peers
Subject: CEQA VMT Transportation Impact Analysis Guidelines
SF19-1023
This memorandum summarizes the City of Petaluma’s VMT Transportation Impact Analysis (TIA)
guidance to project applicants and transportation consultants regarding the need, form, and
methods of evaluating a project’s impacts to VMT for the purposes of CEQA Transportation
section impact analysis. The guidance in this memorandum was developed as part of the City of
Petaluma’s formal SB 743 VMT implementation process and reflects the recommendations of the
Technical Advisory Committee and the decisions of the City Council as part of the formal
implementation process.
It is noted that City staff retain discretion to deviate from the guidance in the memorandum, or
when substantial evidence exists to deviate from the guidance. These VMT TIA Guidelines may be
periodically updated at the staff level to reflect best practices based on industry standards. Also,
the guidance in this memorandum is provided for VMT analysis only, the City may (at its
discretion) require an informational analysis of congestion using Level of Service (LOS) or other
metrics as part of a non-CEQA analysis. The change to VMT analysis as part of the CEQA
Transportation analysis process does not replace the need to study previously-required topics
such as construction phase impacts, impacts to the bicycle, pedestrian and transit modes,
emergency vehicle access and circulation, and the implementation of hazardous design features
and/or incompatible uses of the roadway system.
It is noted that these VMT TIA Guidelines are related to the evaluation of VMT for CEQA
Transportation analysis purposes only. Other recent Senate Bill 743-related policies released by
Caltrans in July 2020 will require that safety impacts are analyzed in the future. Safety analysis
guidelines will be prepared by the City as a future effort after the adoption of the VMT TIA
Guidelines.
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1. When is a TIA Required?
An applicant seeking project approval will submit the proposed project to the City of Petaluma
Planning Division with an application for project review and approval. The project planner will
transmit the application to Public Works for preliminary review, as part of the project review
process. After a preliminary review of the project by Public Works, the applicant will be notified by
the project planner in writing within 30 days of the application submittal date as to whether a TIA
is required. The decision-making process will be based, in part or in whole, on the flow chart
presented in Attachment A.
A TIA and VMT assessment shall be required for a proposed project that does not satisfy any of
the identified project screening criteria (specifics discussed further in Section 2.1):
Small projects
Local serving retail less than 30,000 square feet
Projects in a Low-VMT area
Projects in proximity to a major transit stop
100 percent affordable housing in a jobs-rich area
Transportation projects that will not result in an increase in vehicle capacity or VMT
Projects with drive-throughs are not eligible for screening and must complete a VMT analysis.
In cases where insufficient information is available to make a preliminary assessment of a
proposal’s effect on VMT, additional information may be requested or Public Works staff shall
determine, at their discretion, whether a TIA will be required. The Planning Division may
recommend that a VMT analysis be performed in cases where there is heightened CEQA risk for a
project. Similarly, in cases where City staff have determined that it is in the public interest to
complete a VMT analysis, a TIA may be required at City staff discretion even if the project meets
one of the screening criteria.
A TIA must be prepared under the direction of a registered California traffic engineer or a
registered California civil engineer with documented experience in traffic engineering and
transportation planning. The TIA shall be submitted to Public Works and the Planning Division in a
draft form. Comments relative to the analysis shall be provided by City staff (in writing) to the
project proponent and its engineer so that any necessary revisions can be made prior to final
submittal. The TIA is not deemed complete or final until it incorporates all necessary revisions and
is prepared to the City’s satisfaction.
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2. Analysis Methodology
For purposes of SB 743 compliance and satisfying CEQA Guidelines §15064.3, a VMT analysis
should be conducted for land use projects as deemed necessary by the City Traffic Engineer and
would apply to projects that have the potential to result in VMT in excess of a percentage of the
baseline VMT per capita (i.e., per resident or per employee) for the land use.
2.1. Project Screening Categories
There are six types of screening that may be applied to projects to allow for the bypassing of
project-level VMT assessment. These screening criteria are summarized below:
Small Projects: Projects that generate or attract fewer than 110 trips per day, which is
equivalent to a 15-unit residential project or a non-residential project of 10,000 square
feet or less.
Local Serving Retail: Local-serving retail projects of less than 30,000 square feet may be
screened on the basis that they may attract trips that would otherwise travel longer
distances.
Projects in Low-VMT Area: Residential and office/employment-focused projects that are in
low-VMT areas (based on adopted VMT thresholds of significance) that are similar in
similar to nearby developments in terms of density, mix of uses, and transit accessibility.
Maps of low-VMT areas in the City are presented in Attachment A. It is noted that the
TIA preparer should verify that the data in the maps, such as the baseline year and
consistency of the development type with the SCTA land uses, is still appropriate for use.
If the project is inconsistent with the underlying data (e.g., a single-family project in a
zone with no existing single-family residential uses), then a detailed VMT analysis should
be conducted to determine whether the project exceeds the VMT.
Projects in Proximity to a Major Transit Stop: Projects within one-half mile (walking
distance) of an existing or planned high-quality transit corridor or major transit station.
These areas are generally delineated in the VMT maps in Attachment A; the TIA preparer
must verify that the project site is within the one-half mile walks of the major transit stop.
To qualify for this exemption, the following additional project design criteria must be met:
o Floor Area Ratio (FAR) of 0.75 or more
o Does not include more parking than required by the City of Petaluma
o Is consistent with Plan Bay Area
o Does not replace affordable residential units with a smaller number of moderate- or
high-income residential units (although a small market-rate project could qualify for
small project screening)
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Affordable Housing in Jobs-Rich Areas: Projects with 100 percent affordable housing that
are located in infill locations and areas with a high jobs-housing imbalance.
Transportation Projects: Transit, bicycle, and pedestrian projects, and roadway
maintenance projects that do not result in an increase in vehicle capacity or VMT.
As noted previously, projects with drive-throughs are not eligible for screening and must
complete a VMT analysis unless otherwise exempted by City staff. City staff retain discretion to
deny the use of a screening criteria if substantial evidence (as defined for CEQA purposes) exists
that screening is not appropriate. Also, screening does not necessarily remove the requirement to
analyze VMT for the purposes of the CEQA Air Quality, Greenhouse Gas and Energy analysis
sections. City staff may require that a technical memorandum be prepared to support the
rationale that a project meets screening criteria.
2.2. VMT Assessment for Non-Screened Development
Projects not screened through the steps above should complete VMT analysis and forecasting
through the latest version of the Sonoma County Transportation Authority (SCTA) travel demand
model to determine if the project results in a significant VMT impact. The version of the model
being used should be approved by City staff and the release date of the model should be clearly
documented in the TIA. This analysis should include ”project generated VMT” and "project effect
on VMT” estimates (where applicable) for the project TAZ (or TAZs) under the following scenarios:
Baseline conditions – For residential and retail/commercial service information, baseline
VMT information is available from the SCTA model. For office and employment-focused
uses, baseline VMT information is available from the MTC model or published data
sources from MTC; note that while baseline information of office and employment-
focused projects is based on data from MTC, the SCTA model will be used in the
evaluation of project impacts (see discussion is Section 2.3). Baseline conditions are
defined as at the time of the release of the Notice of Preparation (NOP) when an
Environmental Impact Report is being prepared or upon a determination that the project
application is complete if an Initial study is being prepared. If baseline conditions at the
time of NOP are not suitable based on substantial evidence, a historical baseline may be
used. It is noted that the off-the-shelf SCTA base year (2015) travel demand model does
not include the effects of SMART (which began revenue service in 2017); engineers
completing traffic analyses are advised to justify and document selection of the baseline
year and to secure acceptance by the City. Future iterations of the SCTA travel demand
model base year are expected to include SMART. SCTA updates the travel demand model
every two to three years and the traffic engineer should check to confirm they are using
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data from the latest available model version.
Baseline plus project conditions - The project land use would be added to the project TAZ
or a separate TAZ would be created to contain the project land uses. A full base year
SCTA model run would be performed and VMT changes would be isolated for the project
TAZ and across the full model network. The model output must include reasonableness
checks of the production and attraction balancing to ensure the project effect is
accurately captured. If this scenario results in a significant impact, then a Cumulative
scenario analysis may be required at City staff discretion. Cumulative scenario analysis
may reveal that the baseline plus project significant impact is temporary in nature if
buildout of the General Plan land use pattern and multimodal transportation system
results in a more efficient land use patterns and multimodal transportation connections
(as measured by VMT per capita metrics).
Cumulative conditions (if required) - This data is available from the SCTA model.
Cumulative conditions are defined as Year 2040 conditions and include land use and
transportation network buildout of the adopted City General Plan. Engineers completing
traffic analyses are advised to check the model land use and transportation network
inputs to verify that they represent appropriate Year 2040 assumptions.
Cumulative plus project conditions (if required) – The project land use would be added to
the project TAZ or a separate TAZ would be created to contain the project land uses. A
full Year 2040 SCTA model run would be performed and VMT changes would be isolated
for the project TAZ and across the full model network. The model output must include
reasonableness checks of the production and attraction balancing to ensure the project
effect is accurately captured.
The model output should include VMT per the relevant metric for the land use being studied. The
VMT metrics by land use project type include:
Residential projects: total home-based VMT per resident
Office and other employment-focused projects: total home-based work VMT per
employee
Retail and other commercial service projects: total project effect on VMT within a
geographic area
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Redevelopment projects: total project effect on VMT within a geographic area1
Project-generated VMT shall be extracted from the travel demand forecasting model using the
origin-destination trip matrix and shall multiply that matrix by the final origin-destination
assignment “skim” matrices in the model. The project-effect on VMT in a geographic area shall be
estimated considering all VMT within the geographic boundary; the geographic boundary shall be
defined based on the project’s area of influence. In many cases, project-generated VMT and
project-effect on VMT will be equal; engineers are advised to justify and document this
assumption, if made.
2.3. Split-Model Approach for Office and Employment-Focused Uses
As noted in Section 2.2 and as included in the thresholds for office and employment-focused
uses provide in Section 3, analysis for these uses rely on a metric of total home-based work VMT
per employee measured at the nine-county Bay Area level. This is due to the desire to maintain
consistency with the OPR Technical Advisory. Data from the MTC model (or other published data
from MTC) is suggested for the setting of baseline VMT values for this metric as it provides better
information about home-based work VMT per employee for the entire Bay Area.
While the baseline information is based on the MTC model, the SCTA model should be used in
the evaluation of VMT impacts. The SCTA model has been updated to include trip lengths on
model gateway boundaries (at the border of Sonoma County with neighboring counties) based
on location-based service “Big Data”, thus the SCTA model is able to account for the length of
project trips beyond the county boundary. Based on discussions with SCTA staff, this split-model
approach is valid because the SCTA model does effectively model the length of trips between
Sonoma County and other destinations in the Bay Area through the use of Big Data. As such, the
SCTA model also provides data on the length of trips between Petaluma and Mendocino County,
something that the MTC does not provide well.
Ultimately this split model approach provides for a more conservative calculation because the
roadway network detail in the SCTA model is more robust than the MTC model. Thus, the
calculation using the SCTA model generally leads to slightly higher estimates of home-based
work VMT per worker than the MTC model. Using a higher estimate of the project’s effect on VMT
from the SCTA model versus the comparatively lower baseline value form the MTC model (or
1 For redevelopment projects, City staff retain discretion to require a VMT analysis use the residential,
office/employment, and/or retail thresholds if substantial evidence indicates that the redevelopment metric
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published information) yields a more conservative assessment of the projects CEQA impacts
related to VMT.
2.4. Relationship between VMT and LOS Analyses
As noted previously, an analysis of congestion using Level of Service (LOS) or similar metrics may
continue to be required by the City Traffic Engineer as part of an informational assessment of the
project’s effects on the operations of the City’s circulation system. Guidelines for the conduction
of informational, LOS-based congestion analysis are provided in a separate document. If the City
requires improvement measures that add roadway capacity, the induced VMT effects of these
improvements must be captured in the CEQA VMT analysis. The State Office of Planning and
Research’s Technical Advisory on Evaluating Transportation Impacts in CEQA contains a list of
transportation system improvements that are presumed to not result in induced VMT; many
typical LOS-related improvement strategies (installing traffic signals, installing turn pockets, etc.)
are listed as presumed to not result in induced VMT.
2.5. CEQA Safety Analysis
In July 2020, Caltrans released interim guidance to its districts on how to review potential safety
impacts for projects that affect the state highway system (https://dot.ca.gov/-/media/dot-
media/programs/transportation-planning/documents/sb-743/2020-07-01-interim-ldigr-safety-
guidance-a11y.pdf). Guidelines for safety analysis will be released in the future after the VMT TIA
Guidelines have been adopted, although it is noted that Caltrans may begin to provide safety
analysis-related comments on Notices of Preparation or draft environmental documents at their
discretion.
3. CEQA VMT Impact Thresholds
The following CEQA VMT impact thresholds have been adopted by the City Council through
Resolution XXXXX. Projects resulting in a significant VMT impact are required to implement
mitigation measures to alleviate the significant impact.
A project would result in a significant impact and require mitigation if:
For residential projects: Project total home-based VMT per resident exceeds 16.8% of
the City-wide average. The City-wide average baseline value applies until such time that
the City of Petaluma exceeds the housing allocation for the City as identified in the
Sustainable Communities Strategy (SCS) for the Bay Area region; if the City exceeds the
SCS housing allocation, the nine-county Bay Area regional average applies.
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For office and other employment-focused projects: Project total home-based work
VMT per employee exceeds 16.8% of the nine-county Bay Area regional average
For retail and other commercial service projects: Project results in a net increase in
VMT over the geographic area that the project influences.
For mixed-use and other projects: Project components should be analyzed using the
relevant thresholds for residential, office/employment-focus, or retail/commercial service
projects. The benefit of a mix of uses on-site can and should be included in the analysis.
For transportation projects: Project results in induced travel and an increase in City-
wide VMT2
For redevelopment projects: Project results in increased VMT versus current land uses.
City staff retain discretion to identify the baseline VMT for use in the calculation (i.e.
based on current uses or permitted uses).
4. VMT Mitigation Measures
To mitigate VMT impacts, the following choices are available to the applicant:
1. Modify the project’s built environment characteristics (density, design diversity of uses,
distance to transit, etc.) to reduce VMT generated by the project.
2. Implement Transportation Demand Management (TDM) measures to reduce VMT
generated by the project.
3. Participate in a VMT fee program and/or VMT mitigation exchange/banking program (if
available) to reduce VMT from the project or other land uses to achieve acceptable levels.
Measures appropriate for most of the City of Petaluma are summarized in Chapter 4 of the City’s
Senate Bill 743 Vehicle-Miles Traveled Implementation Report. Other TDM measures may be
included as part of mitigation if substantial evidence exists that they are relevant to the project
being analyzed.
VMT reductions should be evaluated using state-of-the-practice methodologies recognizing that
many of the TDM strategies are dependent on building tenant performance over time. As such,
actual VMT reduction cannot be reliably predicted, and monitoring may be necessary to gauge
performance related to mitigation expectations.
When a project is found to have a significant impact under CEQA, the City of Petaluma requires
developers and the business community to assist in reducing total vehicular trips and VMT by
2 Analysis for non-screened transportation projects require the use of SCTA travel demand model runs for
the No Project and Plus Project scenario and may include an assessment of induced VMT using the UC
Davis Induced Travel Calculator or published literature on the topic (e.g. elasticities from The Fundamental
Law of Road Congestion: Evidence from US Cities. (Duranton and Turner, 2012). 1-68
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implementing TDM plans. The potential of a proposed project to reduce traffic through the use of
a TDM plan should be addressed in the TIA.
If a TDM plan is proposed as a mitigation measure for a project, and the TIA attributes a reduction
in VMT to the TDM plan, the following information must be provided:
1. A detailed description of the major components of the TDM plan and how it would be
implemented and maintained on a continuing basis.
2. Case studies or empirical data that supports the anticipated reduction of traffic attributed
to the TDM plan.
3. Enforcement Measures – how it will be monitored and enforced.
5. TIA Procedures
This section outlines the typical procedure for conducting a Transportation Impact Analysis (TIA)
in Petaluma. The purpose of this procedure is to outline the process for securing necessary City
staff concurrence and feedback on key study parameters, assumptions, results and conclusions
throughout the TIA development process. This typical procedure can be modified at City staff
discretion, but is a useful framework for communication between preparers of TIAs and City staff.
Step 1. Identify Scope of VMT Analysis: Using the flowchart presented in Attachment
A, review the project description and characteristics such as types of uses, size, location,
etc. to determine the level of VMT analysis required. Other required analysis beyond VMT
analysis may include, but are not limited to, safety analysis, construction impact analysis,
analysis of hazardous design features and incompatible uses, emergency vehicle access
and circulation, analysis of the multimodal system (transit, bicycle and pedestrian modes),
and informational LOS analysis.
Step 2. Develop Scope of Work and Submit for Approval: Develop scope of work for
the TIA, including whether documentation will include a formal report or technical
memorandum. Submit scope of work and supporting information and assumptions
behind development of the scope to the City Traffic Engineer for review and approval.
Additional review by other functional groups in the Public Works Department and
Planning Division may be required for approval. Revise scope as necessary based on City
staff comments.
Step 3. Prepare Draft TIA and Submit for Review: Conduct TIA and document in a
formal report or memorandum (documentation assumption to be confirmed as part of
scope review in Step 2). Documentation should include, at a minimum, relevant
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information about the project description, discussion of analysis assumptions, methods
and procedures, summary of calculations and results, and CEQA findings and mitigation
measures (if necessary). It is recommended that the CEQA analysis and informational LOS
analyses be provided in separate sections in the documentation. Submit documentation
to City staff for review and comment. City staff will review the calculations, results and
findings of the TIA and provide questions and comments for the TIA preparer to respond
to.
Step 4. Respond to Comments and Submit for Approval: Revise TIA documentation
based on City comments and respond to questions as appropriate. Submit a redline
version of the documentation with edits and responses to comments (as appropriate).
City staff will review the updated documentation and approve the documentation or
provide additional questions or comments. It is noted that the City strives to approve TIA
reports or memoranda after one round of comments, but the City retains discretion to
request additional information or provide additional comments/questions based on the
responses/modifications provided in the updated TIA documentation.
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Attachment A
Citywide TDM Requirements
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City of Petaluma
Draft Citywide
TDM Requirements
May 2021
prepared by
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Step 1: Transportation CEQA Process
Drive-Through Does the project include a drive-through?
Small Projects Does the project generate less than 110
trips per weekday based on data from the latest version of
the ITE Trip Generation Manual?
Local Retail Is the project local-serving retail (or a local
serving commercial use), and less than 30,000 square feet
in gross floor area?
Near Transit Is the project within 1/2 mile of a major transit
stop, and does the project meet the following design criteria:
• Floor Area Ratio (FAR) of 0.75 or more?
• Does not include more parking than required by the City?
• Is consistent with Plan Bay Area?
• Does not replace affordable residential units with a smaller
number of moderate- or high-income residential units?
Affordable Housing Is the project a residental project
that is located in an infill development area and includes
100% affordable housing?
Low VMT-Generating Based on the map presented
in Step 2 relevant to the project type (residential, local
serving retail/commercial without drive-through, or office/
employment focused uses), is the project located in a low
VMT-generating area (green zones)?
Potential Mitigatable Area Based on the following
map relevant to the project type (residential, local serving
retail/commercial without drive-through, or office/
employment focused uses), is the project located
in a potential mitigatable area (yellow zones)?
* See City of Petaluma’s CEQA VMT Transportation Impact Analysis Guidelines for more information on these steps
YESNO
YESNO
YESNO
YESNO
YESNO
YESNO
YESNO
Project requires VMT analysis and TDM plan
Project requires a VMT analysis and TDM plan.
VMT impacts may not be mitigatable, subject
to the provision of substantial evidence. An
Environmental Impact Report may be needed.
Project requires a VMT analysis and TDM plan.
VMT impacts may be mitigatable, subject
to the provision of substantial evidence. A
Mitigated Negative Declaration is possible.
Project requires a TDM plan - proceed to Step 3 after completing the steps below.
Project may be screened out based on City screening criteria but requires a TDM plan
Project may be screened
out based on City
screening criteria and no
TDM plan is required.
Process is complete.
START HERE
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Step 2: VMT Maps
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Petaluma City - Total Home-Based Vehicle-Miles Traveled Prescreened
TAZ with no Employee (Jobs)
16.8% below Bay Area Region-wide Average
Between 16.8% below Region-wide and Region-wide Average
Above Region-wide Average
Half-mile station buffer
Cities
Petaluma City SB743 - Data from Sonoma County Travel Demand Model
Bay Area Region-Wide Average Total Home-Based WorkVMT per Employee: 22.7
Zones with regionally attracting jobs generate higher VMT per capita compared to those that attractlocal workers. If the density, design, or demographics of a development project do not matchthe existing land uses in a zone, the VMT per capita should be adjusted to account for these factors.
!
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Petaluma City - Total Home-Based Vehicle-Miles Traveled Prescreened
TAZ with no Residents
16.8% below City-wide Average
Between 16.8% below City-wide and City-wide Average
Above City-wide Average
Half-mile station buffer
Cities
Petaluma City SB743 - Data from Sonoma County Travel Demand Model
Petaluma City City-Wide Average Total Home-BasedVMT per Resident: 19.30
Single-family homes generate more VMT per capita, and therefore zones with more single-family homes generate higher VMT per capita compared to those with multi-family housing. If the density, design, or demographics of a developmentproject do not match the existing land uses in a zone, the VMT per capita should be adjusted to account for these factors.
* These values were calculated using the 2015 base year of the August 2020 version of the Sonoma County Transportation Authority (SCTA) travel demand model. This model incorporates ‘Big Data’ to refine trip length estimates for inter-county trips. The 2015 horizon year was chosen as a baseline due to the effects of 2017 and 2019 Sonoma County wildfires and the 2020 COVID-19 pandemic. These values should be updated with new baseline SCTA model information as it becomes available.
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Petaluma City - Total Home-Based Vehicle-Miles Traveled Prescreened
TAZ with no Residents
16.8% below City-wide Average
Between 16.8% below City-wide and City-wide Average
Above City-wide Average
Half-mile station buffer
Cities
Petaluma City SB743 - Data from Sonoma County Travel Demand Model
Petaluma City City-Wide Average Total Home-BasedVMT per Resident: 19.30
Single-family homes generate more VMT per capita, and therefore zones with more single-family homes generate higher VMT per capita compared to those with multi-family housing. If the density, design, or demographics of a developmentproject do not match the existing land uses in a zone, the VMT per capita should be adjusted to account for these factors.
TAZs with no employees (jobs)
Home-Based Work VMT per Employee
TAZs with no residents
Home-Based VMT per Resident
Petaluma citywide average: 19.3
Bay Area regional average: 22.7
16.8% or more below
citywide average
Between 16.8% and
0% below average
Above average
Petaluma Downtown
SMART station
Petaluma North
SMART station
(future)
1/2-mile station buffer
City limits
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Petaluma City - Total Home-Based Vehicle-Miles Traveled Prescreened
TAZ with no Residents
16.8% below City-wide Average
Between 16.8% below City-wide and City-wide Average
Above City-wide Average
Half-mile station buffer
Cities
Petaluma City SB743 - Data from Sonoma County Travel Demand Model
Petaluma City City-Wide Average Total Home-BasedVMT per Resident: 19.30
Single-family homes generate more VMT per capita, and therefore zones with more single-family homes generate higher VMT per capita compared to those with multi-family housing. If the density, design, or demographics of a developmentproject do not match the existing land uses in a zone, the VMT per capita should be adjusted to account for these factors.
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Petaluma City - Total Home-Based Vehicle-Miles Traveled Prescreened
TAZ with no Residents
16.8% below City-wide Average
Between 16.8% below City-wide and City-wide Average
Above City-wide Average
Half-mile station buffer
Cities
Petaluma City SB743 - Data from Sonoma County Travel Demand Model
Petaluma City City-Wide Average Total Home-BasedVMT per Resident: 19.30
Single-family homes generate more VMT per capita, and therefore zones with more single-family homes generate higher VMT per capita compared to those with multi-family housing. If the density, design, or demographics of a developmentproject do not match the existing land uses in a zone, the VMT per capita should be adjusted to account for these factors.
Legend
Data from Sonoma County
Travel Demand Model
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Petaluma City - Total Home-Based Vehicle-Miles Traveled Prescreened
TAZ with no Residents
16.8% below City-wide Average
Between 16.8% below City-wide and City-wide Average
Above City-wide Average
Half-mile station buffer
Cities
Petaluma City SB743 - Data from Sonoma County Travel Demand Model
Petaluma City City-Wide Average Total Home-BasedVMT per Resident: 19.30
Single-family homes generate more VMT per capita, and therefore zones with more single-family homes generate higher VMT per capita compared to those with multi-family housing. If the density, design, or demographics of a developmentproject do not match the existing land uses in a zone, the VMT per capita should be adjusted to account for these factors.
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Step 3: Draft Menu of TDM Measures
Project/Site Level Strategies
Increase diversity of land uses•••HIGHIncrease density•••HIGHImplement car-sharing program•LOWIncrease transit accessibility•••HIGHThese strategies can influence travel behavior for residents, employees, and visitors to a project.
Community Level Strategies
Provide on-site childcare
(SUPPORTIVE)Add affordable housing
(SUPPORTIVE)Implement employee parking "cash-out"(SUPPORTIVE)Collaborate with app-based ridehail services for first/last mile connections
(SUPPORTIVE)Improve existing pathways to meet design standards
(SUPPORTIVE)Implement a commute trip reduction program (commercial uses only)(SUPPORTIVE)Way-finding Signage
(SUPPORTIVE)Provide real-time transit information
(SUPPORTIVE)Support micro-mobility and bike sharing
(SUPPORTIVE)Provide short- and long-term bike parking and supporting services (SUPPORTIVE)On-site TDM Coordinator
(SUPPORTIVE)Encourage tele-commuting••MEDIUMKey
Increase diversity of land uses•••HIGHEffectiveness of Measure
Measures are sorted by effectiveness
(HIGH •••, MEDIUM ••, or LOW •)
(SUPPORTIVE) denotes measures that
meet planning best practices, but whose
effectiveness is unknown for a setting like
Petaluma. Additional study is required to
establish their effectiveness in Petaluma.
Measure Applicability Based on Location
All measures may be
applicable throughout the
City, but marked as most
appropriate for areas in
I green, I yellow, or I gold
in the maps from Step 2.
Provide delivery services
(SUPPORTIVE)Reduce parking supply and un-bundle parking
(SUPPORTIVE)Individual development projects have limited ability to implement these strategies, but may be able to contribute to established strategies through site design or off-site measures via citywide fee programs. These strategies generally have a low effectiveness, which increases when applied to a large population/neighborhood.
* Additional information on measures with quantifiable VMT reductions is provided in Senate Bill 743 Vehicle Miles Traveled Implementation Guidelines (May 2021)...
Incentivize non-vehicular tourism(SUPPORTIVE)Increase transit service frequency and speed•LOWMarket price public parking (on-street)••MEDIUMVision Zero education strategies(SUPPORTIVE)Traffic calming measures and low-stress bike network improvements•LOWIncentivize trips by active transportation•LOWMicro- mobility share program•LOWSubsidize transit passes•LOWSubsidize transit passes•LOW1-75
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Appendix C:
Methodologies to Quantify VMT
Reductions
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APPENDIX C – Methodologies to Quantify VMT Reduction
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Increase Diversity of Urban and Suburban Developments (Mixed Use)
Range of Effectiveness:
0 – 12% vehicle miles traveled (VMT) reduction due to a mix of land uses within a single development
(Ewing and Cervero, 2010).
0.3 – 4% VMT reduction due to change in land use entropy index (i.e., land use mix) within a project’s
sphere of influence (Zhang).
Measure Description:
Having different types of land uses near one another can decrease VMT since trips between land use
types are shorter and may be accommodated by non-auto modes of transport. For example, when
residential areas are in the same neighborhood as retail and office buildings, a resident does not need to
travel outside of the neighborhood to meet his/her trip needs. A description of diverse uses for urban and
suburban areas is provided below (CAPCOA 2010, p. 162)
Urban:
An urban project is predominantly characterized by properties on which various uses, such as office,
commercial, institutional, and residential, are combined in a single building or on a single site in an
integrated development project with functional interrelationships and a coherent physical design. These
mixed-use developments should encourage walking and other non-auto modes of transport from
residential to office/commercial/institutional locations (and vice versa). The residential units should be
within a quarter mile of parks, schools, or other civic uses. These projects minimize the need for external
trips by including services/facilities for day care, banking/ATM, restaurants, vehicle refueling, and
shopping (CAPCOA 2010, p. 162).
Suburban:
A suburban project has at least three of the following on site and/or offsite within a quarter mile:
residential development, retail development, park, open space, or office. These mixed-use developments
should encourage walking and other non-auto modes of transport from residential to office/commercial
locations (and vice versa). These projects minimize the need for external trips by including
services/facilities for day care, banking/ATM, restaurants, vehicle refueling, and shopping (CAPCOA 2010,
p. 162).
Measure Applicability:
Urban and suburban context
Negligible impact in a rural context (unless the project is a master-planned community)
Appropriate for mixed-use projects
Inputs:
The following information needs to be provided by the project applicant:
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Percentage of each land use type in the project
Mitigation Method:
% 𝑅𝐿𝑅 𝑅𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖 = 𝐿𝑎𝑖𝑎 𝑅𝑖𝑎× 𝐴𝐶�ℎ𝑟𝑐𝑟𝑟�ℎ𝑟𝑦
(𝑖𝑖𝑖 𝑖𝑖 𝑎𝑖𝑎𝑎𝑎𝑎 15% 𝑎𝑖𝑖 𝑖𝑖𝑖−𝑖𝑖𝑖𝑖 𝑖𝑖𝑖𝑖𝑖 𝑎𝑖𝑎 25% 𝑎𝑖𝑖 𝑎𝑖𝑖𝑖𝑖𝑖𝑎 𝑖𝑖𝑖𝑖𝑖)
Where:
𝐿𝑎𝑖𝑎 𝑅𝑖𝑎=(𝐿𝑎𝑖𝑎 𝑅𝑖𝑎 𝐻𝑖𝑎𝑎𝑖−0.15)0.15⁄ (𝑖𝑖𝑖 𝑖𝑖 𝑎𝑖𝑎𝑎𝑎𝑎 500% 𝑖𝑖𝑎𝑖𝑎𝑎𝑖𝑎)
𝐿𝑎𝑖𝑎 𝑅𝑖𝑎 𝐻𝑖𝑎𝑎𝑖=−𝑎ln(6)⁄
𝑎=∑𝑎�ℎ6�ℎ=1 × ln (𝑎�ℎ) (Song and Knaap, 2004)
𝑎�ℎ=𝐴𝑖𝑖𝑖𝑎𝑖𝑖𝑎 𝑎𝑖𝑖𝑖𝑖 𝑎𝑖𝑎𝑎 𝑖𝑎 𝑖𝑎𝑖𝑎 𝑖𝑖𝑎 𝑖𝑖𝑖𝑖𝑎𝑖 𝑖𝑖𝑖𝑎𝑖𝑎 𝑎𝑎𝑎𝑖 𝑖𝑎 𝑖𝑖𝑖𝑖𝑎𝑎𝑖 𝑖𝑎𝑖𝑎 𝑎𝑖𝑎𝑎⁄
o 𝑎1 =𝑅𝑖𝑖𝑎𝑖𝑎 𝑎𝑎𝑖𝑖𝑖𝑖 𝑖𝑎𝑖𝑖𝑎𝑎𝑖𝑖𝑖𝑎𝑖
o 𝑎2 =𝐿𝑖𝑖𝑖𝑖𝑎𝑎𝑖𝑖𝑖𝑖 𝑖𝑎𝑖𝑖𝑎𝑎𝑖𝑖𝑖𝑎𝑖
o 𝑎3 =𝐴𝑖𝑖𝑖𝑎𝑖𝑎𝑖𝑎𝑖
o 𝑎4 =𝐻𝑖𝑎𝑖𝑖𝑖𝑖𝑖𝑎𝑖
o 𝑎5 =𝐻𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑎𝑖
o 𝑎6 =𝑃𝑎𝑖𝑖
𝐴𝐶�ℎ𝑟𝑐𝑟𝑟�ℎ𝑟𝑦 =𝐴𝑖𝑎𝑖𝑖𝑖𝑎𝑖𝑖𝑖 𝑖𝑎 𝑅𝐿𝑅 𝑖𝑖𝑖ℎ 𝑖𝑎𝑖𝑖𝑖𝑎𝑎𝑖 𝑖𝑖 𝑖𝑎𝑖𝑎 𝑖𝑖𝑎 𝑖𝑖𝑎𝑎𝑖=0.02 𝑖𝑖 0.08 [4]
If land use 𝑎�ℎ is not present, set 𝑎�ℎ equal to 0.01
Discussion:
In the above calculation, a land use index of 0.15 is used as a baseline representing a development with a
single land use. There are two separate maxima that should be noted: an effective cap of 500% on the
allowable percentage increase of land use index and a cap of 15% and 25% on percent VMT reduction for
non-work and commute trips, respectively. The 500 percent cap reflects the expected change in a land use
index from 0.15 to 0.90, or from single use to a nearly equal balance of all six uses included in this
method. The purpose for the 15% and 25% caps is to limit the influence of any single environmental
factor (such as diversity). This emphasizes that community designs that implement multiple land use
strategies (such as density, design, diversity, etc.) will show more of a reduction than relying on
improvements from a single land use factor (CAPCOA 2010, p. 164).
The land use (or entropy) index measurement looks at the mix of land uses of a development. An index of
0 indicates a single land use while 1 indicates a full mix of uses. The preferred elasticity of VMT with
respect to the land use mix index for Riverside County is 0.02, per work examining policy effects on VMT
conducted by Salon et al for the Air Resource Board.
Example:
Sample calculations are provided below:
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90% single family homes, 10% commercial
𝐿𝑎𝑖𝑎 𝑖𝑖𝑎 𝑖𝑖𝑎𝑎𝑖=−[0.9 × ln(0.9)+0.1 × ln(0.1)+4 × 0.01 × ln(0.01)]ln (6)⁄=0.3
𝐿𝑖𝑖 𝑅𝑎𝑖𝑎𝑎 % 𝑅𝐿𝑅 𝑅𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖=(0.3 −0.15)0.15⁄× 0.02 =2%
1/6 single family, 1/6 multi-family, 1/6 commercial, 1/6 industrial, 1/6 institutional, 1/6 parks
𝐿𝑎𝑖𝑎 𝑖𝑖𝑎 𝑖𝑖𝑎𝑎𝑖=−[6 × 0.17 × ln(0.17)]ln (6)⁄=1
𝐻𝑖𝑎ℎ 𝑅𝑎𝑖𝑎𝑎 % 𝑅𝐿𝑅 𝑅𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖 (𝑖𝑎𝑖𝑎 𝑖𝑖𝑎 𝑖𝑖𝑎𝑎𝑖=1)
𝐿𝑎𝑖𝑎 𝑖𝑖𝑎=(1 −0.15)0.15⁄=5.6 𝑖𝑖 566%. 𝑅𝑖𝑖𝑎𝑎 𝑖ℎ𝑖𝑖 𝑖𝑖 𝑎𝑖𝑎𝑎𝑖𝑎𝑖 𝑖ℎ𝑎𝑖 500%,𝑖𝑎𝑖 𝑖𝑖 500%
% 𝑅𝐿𝑅 𝑅𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖=(5 × 0.02)= 10%
References:
Ewing, R. and Cervero, R. (2010). Travel and the Built Environment - A Meta-Analysis. Journal of the
American Planning Association,76(3),265-294. Cited in California Air Pollution Control Officers Association.
(2010). Quantifying Greenhouse Gas Mitigation Measures. Retrieved from: http://www.capcoa.org/wp-
content/uploads/2010/11/CAPCOA-Quantification-Report-9-14-Final.pdf
Frank, L., Greenwald, M., Kavage, S. and Devlin, A. (2011). An Assessment of Urban Form and Pedestrian
and Transit Improvements as an Integrated GHG Reduction Strategy. WSDOT Research Report WA-RD
765.1. Washington State Department of Transportation. Retrieved from:
http://www.wsdot.wa.gov/research/reports/fullreports/765.1.pdf
Nasri, A. and Zhang, L. (2012). Impact of Metropolitan-Level Built Environment on Travel Behavior.
Transportation Research Record: Journal of the Transportation Research Board, 2323(1), 75-79.
Sadek, A. et al. (2011). Reducing VMT through Smart Land-Use Design. New York State Energy Research
and Development Authority. Retrieved from: https://www.dot.ny.gov/divisions/engineering/technical-
services/trans-r-and-d-repository/C-08-29%20Final%20Report_December%202011%20%282%29.pdf
Salon, D., Boarnet, M. G., Handy, S., Spears, S., & Tal, G. (2012). How do local actions affect VMT? A critical
review of the empirical evidence. Transportation research part D: transport and environment, 17(7), 495-
508
Song, Y., and Knaap, G., “Measuring the effects of mixed land uses on housing values.” Regional Science
and Urban Economics 34 (2004) 663-680.(p. 669)
http://urban.csuohio.edu/~sugie/papers/RSUE/RSUE2005_Measuring%20the%20effects%20of%20mixed%
20land%20use.pdf
Spears, S.et al. (2014). Impacts of Land-Use Mix on Passenger Vehicle Use and Greenhouse Gas Emissions-
Policy Brief and Technical Background Document. California Air Resources Board. Retrieved from:
https://arb.ca.gov/cc/sb375/policies/policies.htm
Quantifying Greenhouse Gas Mitigation Measures, California Air Pollution Control Officers Association
(CAPCOA), 2010. Chapter 3.1.3 Increase Diversity of Urban and Suburban Developments (Mixed Use).
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Zhang, Wengia et al. "Short- and Long-Term Effects of Land Use on Reducing Personal Vehicle Miles of
Travel."
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Increase Residential Density
Range of Effectiveness:
0.4% – 10.75% VMT reduction due to increasing residential density
Measure Description:
Designing the Project with increased densities, where allowed by the General Plan and/or Zoning
Ordinance reduces GHG emissions associated with traffic in several ways. Density is usually measured in
terms of persons, jobs, or dwellings per unit area. Increased densities affect the distance people travel and
provide greater options for the mode of travel they choose. This strategy also provides a foundation for
implementation of many other strategies which would benefit from increased densities. For example,
transit ridership increases with density, which justifies enhanced transit service.
The reductions in GHG emissions are quantified based on reductions to VMT. The relationship between
density and VMT is described by its elasticity (CAPCOA 2010, p. 155). The range of reductions is based on
a range of elasticities from -0.04 to -0.22. The low end of the reductions represents a -0.04 elasticity of
demand in response to a 10% increase in residential units or employment density and a -0.22 elasticity in
response to 50% increase to residential/employment density.
Measure Applicability:
Urban and suburban context
o Negligible impact in a rural context
Appropriate for residential, retail, office, industrial, and mixed-use projects
Inputs:
The following information needs to be provided by the project applicant:
Number of housing units per acre or jobs per job acre
Mitigation Method:
% 𝑅𝐿𝑅 𝑅𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖=𝐴∗𝐴 [𝑖𝑖𝑖 𝑖𝑖 𝑎𝑖𝑎𝑎𝑎𝑎 30%]
Where:
A = Percentage increase in housing units per acre or jobs per job acre = (number of housing units per
acre or jobs per job acre – number of housing units per acre or jobs per job acre for typical ITE
development) / (number of housing units per acre or jobs per job acre for typical ITE development). For
small and medium sites (less than ½ mile in radius) the calculation of housing and jobs per acre should be
performed for the development site as a whole, so that the analysis does not erroneously attribute trip
reduction benefits to measures that simply shift jobs and housing within the site with no overall increase
in site density. For larger sites, the analysis should address the development as several ½-mile-radius
sites, so that shifts from one area to another would increase the density of the receiving area but reduce
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the density of the donating area, resulting in trip generation rate decreases and increases, respectively,
which cancel one another.
B = Elasticity of VMT with respect to density (from literature)
Detail:
A: [not to exceed 500% increase]
o If housing: (Number of housing units per acre – 7.6) / 7.6
o If jobs: Number of jobs per acre – 20) / 20
B: -0.04 elasticity in response to a 10% increase in residential units or employment density and a -
0.22 elasticity in response to 50% increase to residential/employment density
Discussion:
The VMT reductions for this strategy are based on changes in density versus the typical suburban
residential and employment densities in North America (referred to as “ITE densities”). These densities are
used as a baseline to mirror those densities reflected in the ITE Trip Generation Manual, which is the
baseline method for determining VMT. There are two separate maxima noted in the fact sheet: a cap of
500% on the allowable percentage increase of housing units or jobs per acre (variable A) and a cap of
30% on % VMT reduction. The rationale for the 500% cap is that there are diminishing returns to any
change in environment. For example, it is reasonably doubtful that increasing residential density by a
factor of six instead of five would produce any additional change in travel behavior. The purpose for the
30% cap is to limit the influence of any single environmental factor (such as density). This emphasizes that
community designs that implement multiple land use strategies (such as density, design, diversity, etc.)
will show more of a reduction than relying on improvements from a single land use factor.
References:
Boarnet, M. and Handy, S. (2014). Impacts of Residential Density on Passenger Vehicle Use and
Greenhouse Gas Emissions - Policy Brief and Technical Background Document. California Air Resources
Board. Retrieved from: https://arb.ca.gov/cc/sb375/policies/policies.htm
Quantifying Greenhouse Gas Mitigation Measures, California Air Pollution Control Officers Association
(CAPCOA), 2010. Chapter 3.1.1 Increase Density
Stevens, M. (2017). Does Compact Development Make People Drive Less? Journal of the American
Planning Association, 83(1), 7-18.
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Increase Transit Accessibility
Range of Effectiveness:
1) 0 – 5.8% VMT reduction
VMT reduction when transit station is provided within 1/2 mile of development
(compared to VMT for sites located outside 1/2 mile radius of transit). Locating high
density development within 1/2 mile of transit will facilitate the use of transit by people
traveling to or from the Project site. The use of transit results in a mode shift and
therefore reduced VMT.
2) 0 – 7.3% VMT reduction
Reduction in vehicle trips due to implementing TOD. A project with a
residential/commercial center designed around a rail or bus station, is called a transit-
oriented development (TOD). The project description should include, at a minimum, the
following design features:
• A transit station/stop with high-quality, high-frequency bus service located
within a 5-10 minute walk (or roughly ¼ mile from stop to edge of
development), and/or
• A rail station located within a 20 minute walk (or roughly ½ mile from station
to edge of development)
• Fast, frequent, and reliable transit service connecting to a high percentage of
regional destinations
• Neighborhood designed for walking and cycling
Measure Description:
Locating a project with high density near transit will facilitate the use of transit by people traveling to or
from the Project site. The use of transit results in a mode shift and therefore reduced VMT. A project with
a residential/commercial center designed around a rail or bus station, is called a transit-oriented
development (TOD). The project description should include, at a minimum, the following design features:
A transit station/stop with high-quality, high-frequency bus service located within a 5-10 minute
walk (or roughly ¼ mile from stop to edge of development), and/or
A rail station located within a 20 minute walk (or roughly ½ mile from station to edge of
development)
Fast, frequent, and reliable transit service connecting to a high percentage of regional
destinations
Neighborhood designed for walking and cycling
Measure Applicability:
Urban and suburban context
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Appropriate in a rural context if development site is adjacent to a commuter rail station with
convenient rail service to a major employment center
Appropriate for residential, retail, office, industrial, and mixed-use projects
Inputs:
The following information needs to be provided by the project applicant:
Distance to transit station in project
Mitigation Method:
% 𝑅𝐿𝑅 𝑅𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖=𝑅𝑖𝑎𝑖𝑖𝑖𝑖∗𝐴[𝑖𝑖𝑖 𝑖𝑖 𝑎𝑖𝑎𝑎𝑎𝑎 30%]
Where:
Transit = Increase in transit mode share = % transit mode share for project - % transit mode share
for typical ITE development
% transit mode share for project (see Table)
Distance to transit Transit mode share calculation
equation
Distance to transit Transit mode share calculation
equation
(where x = distance of project to transit) (where x = distance of project to transit)
0 – 0.5 miles -50*x + 38 0 – 0.5 miles -50*x + 38
0.5 to 3 miles -4.4*x + 15.2 0.5 to 3 miles -4.4*x + 15.2
> 3 miles no impact
B = adjustments from transit ridership increase to VMT (0.67)
Discussion:
The purpose for the 30% cap on percent VMT reduction is to limit the influence of any single
environmental factor (such as transit accessibility). This emphasizes that community designs that
implement multiple land use strategies (such as density, design, diversity, transit accessibility, etc.) will
show more of a reduction than relying on improvements from a single land use factor.
References:
1) Lund, H. et al. (2004). Travel Characteristics of Transit-Oriented Development in California. Oakland,
CA: Bay Area Rapid Transit District, Metropolitan Transportation Commission, and Caltrans.
Tal, G. et al. (2013). Policy Brief on the Impacts of Transit Access (Distance to Transit) Based on a
Review of the Empirical Literature. California Air Resources Board. Retrieved from:
https://www.arb.ca.gov/cc/sb375/policies/transitaccess/transit_access_brief120313.pdf
2) Zamir, K. R. et al. (2014). Effects of Transit-Oriented Development on Trip Generation, Distribution,
and Mode Share in Washington, D.C., and Baltimore, Maryland. Transportation Research Record:
Journal of the Transportation Research Board. 2413, 45–53. DOI: 10.3141/2413-05
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Encourage Telecommuting and Alternative Work Schedules
Range of Effectiveness:
0.2 – 4.5% commute VMT reduction.
Measure Description:
Encouraging telecommuting and alternative work schedules reduces the number of commute trips and
therefore VMT traveled by employees. Alternative work schedules could take the form of staggered
starting times, flexible schedules, or compressed work weeks (CAPCOA 2010, p. 236).
Measure Applicability:
Urban, suburban, and rural context
Appropriate for retail, office, industrial, and mixed-use projects
VMT reduction is dependent on the performance of individual building tenants and may change
over time. On-going monitoring and adjustment is necessary to achieve sustained reductions in
VMT.
Inputs:
The following information needs to be provided by the project applicant:
Percentage of employees participating (1 – 25%)
Telecommute elasticity (see discussion below)
Mitigation Method:
% 𝐴𝑖𝑖𝑖𝑖𝑖𝑎 𝑅𝐿𝑅 𝑅𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖=𝐴𝑆𝑐𝑙𝑐𝑐𝑜𝑙𝑙𝑟𝑟𝑐∗𝑅𝑎𝑖𝑎𝑎𝑖𝑖𝑖𝑖𝑖𝑎 𝐴𝑎𝑖𝑖𝑎
Where:
𝑅𝑎𝑖𝑎𝑎𝑖𝑖𝑖𝑖𝑖𝑎 𝐴𝑎𝑖𝑖𝑎=% 𝑎ℎ𝑎𝑖𝑎𝑎 𝑖𝑖 𝑖𝑖𝑖𝑖𝑎𝑖𝑖 𝑖𝑎𝑖𝑎𝑎𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑎 𝑖𝑖𝑖ℎ 𝑅𝐴𝐿 𝑃𝑖𝑖𝑎𝑖𝑎𝑖
𝐴𝑆𝑐𝑙𝑐𝑐𝑜𝑙𝑙𝑟𝑟𝑐=% 𝑎ℎ𝑎𝑖𝑎𝑎 𝑖𝑖 𝑅𝐿𝑅 𝑖𝑎𝑖 % 𝑎ℎ𝑎𝑖𝑎𝑎 𝑖𝑖 𝑖𝑖𝑖𝑖𝑎𝑖𝑖 𝑖𝑎𝑖𝑎𝑎𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑎
𝐴𝑆𝑐𝑙𝑐𝑐𝑜𝑙𝑙𝑟𝑟𝑐= 0.18 𝑖𝑖 0.90
Discussion:
Telecommute Delta and ETelecommute should consider the potential for building tenants to change over time.
Higher values require the employer at the site to be known and unlikely to change over time. ETelecommute
will be lower in places with higher non-drive alone mode share, and higher in places with more drive
alone vehicle mode share.
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References:
Handy, Tal, Boarnet. 2013. "Policy Brief on the Impacts of Telecommuting Based on a Review of the
Empirical Literature."
https://www.arb.ca.gov/cc/sb375/policies/telecommuting/telecommuting_brief120313.pdf
Quantifying Greenhouse Gas Mitigation Measures, California Air Pollution Control Officers Association
(CAPCOA), 2010. Chapter 3.4.6 Encourage Telecommuting and Alternative Work Schedules
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Provide Pedestrian Network Improvements
Range of Effectiveness:
0.5 – 5.7% VMT reduction
Measure Description:
Providing pedestrian access at and near a project site encourages people to walk instead of drive,
presuming that desirable destinations exist within walking distance of the project. This mode shift results
in people driving less and thus a reduction in VMT. The pedestrian access network should internally link all
uses and connect to all existing or planned external streets and pedestrian facilities contiguous with the
project site. It should also minimize barriers to pedestrian access and interconnectivity. Physical barriers
such as walls, landscaping, and slopes that impede pedestrian circulation should be eliminated (CAPCOA
2010, p. 186).
Measure Applicability:
Urban, suburban, and rural context
Appropriate for residential, retail, office, industrial, and mixed-use projects
Reduction benefit only occurs if the project has both pedestrian network improvements on site
and connections to the larger off-site network. All calculations should incorporate the status of
the network in the project’s walkshed (i.e., within a ¼ mile radius).
Desirable destinations external to the project site must be within walking distance (i.e., preferably
within a ¼ mile and no greater than ½ mile).
Inputs:
The project applicant must provide information regarding pedestrian access and connectivity within the
project and to/from off-site destinations. The change in sidewalk coverage should represent the share of
quality sidewalk and pedestrian facilities available in the surrounding area; for instance, if one block-face
of ten is missing sidewalks, the existing coverage is 90%. This measure is not effective in reducing VMT in
locations with already fully-developed, high quality sidewalk networks.
Mitigation Method:
% 𝑅𝐿𝑅 𝑅𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖=𝐴𝑃𝑐𝑐𝐴𝑐𝑐𝑐𝑟𝑟× 𝑅𝑖𝑎𝑎𝑖𝑎𝑖𝑖 𝐴𝑎𝑖𝑖𝑎
Where:
𝐴𝑃𝑐𝑐𝐴𝑐𝑐𝑐𝑟𝑟=% 𝐴ℎ𝑎𝑖𝑎𝑎 𝑖𝑖 𝑅𝐿𝑅 𝑖𝑎𝑖 % 𝐻𝑖𝑎𝑖𝑎𝑎𝑖𝑎 𝑖𝑖 𝑅𝑖𝑎𝑎𝑖𝑎𝑖𝑖 𝐴𝑖𝑖𝑎𝑖𝑎𝑎𝑎
𝑅𝑖𝑎𝑎𝑖𝑎𝑖𝑖 𝐴𝑎𝑖𝑖𝑎=𝐴𝑖𝑖𝑖𝑖𝑎𝑎 𝑎ℎ𝑎𝑖𝑎𝑎 𝑖𝑖 𝑖𝑖𝑎𝑎𝑖𝑎𝑖𝑖 𝑎𝑖𝑖𝑎𝑖𝑎𝑎𝑎 𝑎𝑖𝑖𝑖𝑎𝑖𝑎𝑎 𝑖𝑖 𝑎𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖𝑎 𝑎𝑖𝑖𝑎𝑖𝑖𝑖𝑖𝑖
Detail:
𝐴𝑃𝑐𝑐𝐴𝑐𝑐𝑐𝑟𝑟=0.0 𝑖𝑖 0.14 (0.07 preferred in absence of other data)
𝑅𝑖𝑎𝑖𝑎𝑖𝑖 𝐴𝑎𝑖𝑖𝑎= 5% 𝑖𝑖 100%
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Discussion:
Pedestrian Access Elasticity varies at the local level and is dependent on many factors such as the urban
form of the immediate area and population characteristics. When reliable studies are available and
applicable to the project area, this elasticity should be calculated. Otherwise, 0.07 is recommended based
on the range provided by Handy, S. et al.
References:
Handy, S. et al. (2014). Impacts of Pedestrian Strategies on Passenger Vehicle Use and Greenhouse Gas
Emissions – Policy Brief and Technical Background Document. California Air Resources Board. Retrieved
from: https://arb.ca.gov/cc/sb375/policies/policies.htm
Quantifying Greenhouse Gas Mitigation Measures, California Air Pollution Control Officers Association
(CAPCOA), 2010. Chapter 3.2.1 Provide Pedestrian Network Improvements.
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Provide Traffic Calming Measures
Range of Effectiveness:
0 – 1.7% VMT reduction
Measure Description:
Providing traffic calming measures encourages people to walk or bike instead of using a vehicle. This
mode shift results in a decrease in VMT. Project design should include pedestrian/bicycle safety and traffic
calming measures in excess of jurisdiction requirements. Roadways should be designed to reduce motor
vehicle speeds and encourage pedestrian and bicycle trips with traffic calming features. Traffic calming
features may include: marked crosswalks, count-down signal timers, curb extensions, speed tables, raised
crosswalks, raised intersections, median islands, tight corner radii, roundabouts or mini-circles, on-street
parking, planter strips with street trees, chicanes/chokers, etc. (CAPCOA 2010, p. 190).
Measure Applicability:
Urban, suburban, and rural context
Appropriate for residential, retail, office, industrial and mixed-use projects
Inputs:
The following information needs to be provided by the project applicant:
Percentage of streets within project with traffic calming improvements
Percentage of intersections within project with traffic calming improvements
Mitigation Calculation:
The VMT reduction is a function of the percentage of streets and intersections within the project with
traffic calming improvements based on the following look up table.
% VMT Reduction % of Streets with Improvements
25% 50% 75% 100%
% of
Intersections
with
Improvements
25% 0.425% 0.425% 0.85% 0.85%
50% 0.425% 0.85% 0.85% 1.275%
75% 0.85% 0.85% 1.275% 1.275%
100% 0.85% 1.275% 1.275% 1.7%
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Discussion:
The table above allows the project applicant to calculate a VMT reduction estimate based on the project’s
street and intersection design with respect to traffic calming. The applicant should look at the rows on the
left and choose the percent of intersections within the project which will have traffic calming
improvements. Then, the applicant should look at the columns along the top and choose the percent of
streets within the project which will have traffic calming improvements. The intersection cell of the row
and column selected in the matrix is the VMT reduction estimate.
Though the literature provides some difference between a suburban and urban context, the difference is
small and thus the lower VMT reduction estimate was used to be applied to all contexts. Rural context is
not specifically discussed in the literature but is presumed to have little to no effect on VMT reduction due
to the long-distances between trip origins and destinations.
Research by Zahabi, S. et al. attributes up to a 1.7% VMT reduction to traffic calming measures. The table
above illustrates the range of VMT reductions based on the percent of streets and intersections with
traffic calming measures implemented. CAPCOA 2010 used a range of 0.25% to 1% for VMT reduction.
The VMT reductions were updated using the same methodology to allow for reductions up to 1.7%.
Because of the high potential for double-counting, caution should be used when combining this measure
with “Provide Pedestrian Network Improvements.”
References:
California Air Resources Board. (2016). Greenhouse Gas Quantification Methodology for the California
Transportation Commission Active Transportation Program Greenhouse Gas Reduction Fund Fiscal Year
2016-17. Retrieved from: https://www.arb.ca.gov/cc/capandtrade/auctionproceeds/ctc_atp_finalqm_16-
17.pdf.
Quantifying Greenhouse Gas Mitigation Measures, California Air Pollution Control Officers Association
(CAPCOA), 2010. Chapter 3.2.2 Provide Traffic Calming Measures.
Zahabi, S. et al. (2016). Exploring the link between the neighborhood typologies, bicycle infrastructure and
commuting cycling over time and the potential impact on commuter GHG emissions. Transportation
Research Part D: Transport and Environment. 47, 89-103.
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Implement Market Price Public Parking (On-Street)
Range of Effectiveness:
2.8% - 14.5% VMT reduction.
Measure Description:
Implement a pricing strategy for parking by pricing all central business district/employment center/retail
center on-street parking. It will be priced to encourage park once" behavior. The benefit of this measure
above that of paid parking at the project only is that it deters parking spillover from project supplied
parking to other public parking nearby, which undermine the vehicle miles traveled (VMT) benefits of
project pricing. It may also generate sufficient area-wide mode shifts to justify increased transit service to
the area.
The VMT reduction applies to VMT from visitor/customer trips only. Reductions higher than top end of
range from CAPCOA report apply only in conditions with highly constrained on-street parking supply and
lack of comparably priced off-street parking.
Inputs:
The following information needs to be provided by the project applicant:
Location of project site: low density suburb, suburban center, or urban location
Percent increase in on-street parking prices (minimum 25% needed)
Mitigation Method:
% 𝑅𝐿𝑅 𝑅𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖=𝑃𝑎𝑖𝑖$∗𝐴
Where:
𝑃𝑎𝑖𝑖$=𝑃𝑎𝑖𝑎𝑎𝑖𝑖 𝑖𝑖𝑎𝑖𝑎𝑎𝑖𝑎 𝑖𝑖 𝑖𝑖 𝑖𝑖𝑖𝑎𝑎𝑖 𝑖𝑎𝑖𝑖𝑖𝑖𝑎 𝑖𝑖𝑖𝑎𝑎𝑖 (𝑖𝑖𝑖𝑖𝑖𝑖𝑖 25% 𝑖𝑖𝑎𝑖𝑎𝑎𝑖𝑎)
𝐴=𝐴𝑖𝑎𝑖𝑖𝑖𝑎𝑖𝑖𝑖 𝑖𝑎 𝑅𝐿𝑅 𝑖𝑖𝑖ℎ 𝑖𝑎𝑖𝑖𝑎𝑎𝑖 𝑖𝑖 𝑖𝑎𝑖𝑖𝑖𝑖𝑎 𝑖𝑖𝑖𝑎𝑎
Discussion:
The range of parking price increases should be a minimum of 25% and a maximum of 50%. The minimum
is based on Moving Cooler discussions, which state that a less than 25% increase would not be a sufficient
amount to reduce VMT. The case study looked at a 50% price increase, and thus no conclusions can be
made on the elasticities above a 50% increase. This strategy may certainly be implemented at a higher
price increase, but VMT reductions should be capped at results from a 50% increase to be conservative.
References:
Clinch, J.P. and Kelly, J.A. (2003). Temporal Variance Of Revealed Preference On-Street Parking Price
Elasticity. Dublin: Department of Environmental Studies, University College Dublin. Retrieved from:
http://www.ucd.ie/gpep/research/workingpapers/2004/04-02.pdf. Cited in Victoria Transport Policy
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Institute (2017). Transportation Elasticities: How Prices and Other Factors Affect Travel Behavior. Retrieved
from: http://www.vtpi.org/tdm/tdm11.htm
Hensher, D. and King, J. (2001). Parking Demand and Responsiveness to Supply, Price and Location in
Sydney Central Business District. Transportation Research A. 35(3), 177-196.
Millard-Ball, A. et al. (2013). Is the curb 80% full or 20% empty? Assessing the impacts of San Francisco's
parking pricing experiment. Transportation Research Part A. 63(2014), 76-92.
Shoup, D. (2011). The High Cost of Free Parking. APA Planners Press. p. 290. Cited in Pierce, G. and Shoup,
D. (2013). Getting the Prices Right. Journal of the American Planning Association. 79(1), 67-81.
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Increase Transit Service Frequency/Speed
Range of Effectiveness:
0.03 – 6.3% VMT reduction.
Measure Description:
This measure reduces transit-passenger travel time through reduced headways and increased speed and
reliability. This makes transit service more attractive and may result in a mode shift from auto to transit
which reduces VMT (CAPCOA 2010, p. 280).
Inputs:
The following information needs to be provided by the project applicant:
Percentage reduction in headways (increase in frequency) for applicable transit routes
Level of implementation
Project setting: urban center, urban, suburban
Existing transit mode share
Mitigation Method:
% 𝑅𝐿𝑅 𝑅𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖=𝐻𝑎𝑎𝑎𝑖𝑎𝑖× 𝐴× 𝐴× 𝐿𝑖𝑎𝑎
Where:
𝐻𝑎𝑎𝑎𝑖𝑎𝑖=% 𝑖𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖 𝑖𝑖 ℎ𝑎𝑎𝑎𝑖𝑎𝑖𝑖
𝐴=𝐴𝑖𝑎𝑖𝑖𝑖𝑎𝑖𝑖𝑖 𝑖𝑎 𝑖𝑖𝑎𝑖𝑖𝑖𝑖 𝑖𝑖𝑎𝑎𝑖𝑖ℎ𝑖𝑖 𝑖𝑖𝑖ℎ 𝑖𝑎𝑖𝑖𝑎𝑎𝑖 𝑖𝑖 𝑖𝑖𝑎𝑖𝑎𝑎𝑖𝑎𝑎 𝑎𝑖𝑎𝑖𝑖𝑎𝑖𝑎𝑖 𝑖𝑎 𝑖𝑎𝑖𝑖𝑖𝑎𝑎
𝐴=𝑅𝑎𝑖𝑖𝑖 𝑖𝑎 𝑖𝑎ℎ𝑖𝑎𝑖𝑎 𝑖𝑖𝑖𝑖𝑖 𝑖𝑎𝑎𝑖𝑎𝑎𝑎 𝑖𝑖 𝑖𝑖𝑖𝑎𝑎𝑖 𝑖𝑎 𝑖𝑎𝑖 𝑖𝑖𝑎𝑖𝑖𝑖𝑖 𝑖𝑖𝑎𝑎𝑖𝑖
𝐿𝑖𝑎𝑎=𝐴𝑖𝑖𝑖𝑖𝑖𝑖𝑎 𝑖𝑖𝑎𝑖𝑖𝑖𝑖 𝑖𝑖𝑎𝑎 𝑖ℎ𝑎𝑖𝑎
Detail:
𝐴=0.50
𝐴=25% 𝑖𝑖 75%
Discussion:
A 1% reduction in headways leads to 0.5% increase in transit ridership. This change is translated into a
VMT reduction by applying a mode shift adjustment to account for new transit trips that do not represent
displaced vehicle trips in addition to considering the existing transit mode share.
Variable C should be calculated based on local data. It is calculated by taking the length of an average
transit trip within the sphere of influence of the project divided by the average vehicle trip length within
the sphere of influence of the project.
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References:
Handy, Lovejoy, Boarnet, Spears. 2013. "Impacts of Transit Service Strategies on Passenger Vehicle Use
and Greenhouse Gas Emissions." http://www.arb.ca.gov/cc/sb375/policies/transitservice/transit_brief.pdf
Litman, T. (2004). Transit price elasticities and cross-elasticities. Journal of Public Transportation, 7(2), 3.
Taylor, B. D., Miller, D., Iseki, H., & Fink, C. (2009). Nature and/or nurture? Analyzing the determinants of
transit ridership across US urbanized areas. Transportation Research Part A: Policy and Practice, 43(1), 60-
77.
Quantifying Greenhouse Gas Mitigation Measures, California Air Pollution Control Officers Association
(CAPCOA), 2010. Chapter 3.5.4 Implement Transit Service Frequency/Speed
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Implement Car-Sharing Program
Range of Effectiveness:
0.3 – 1.6% VMT reduction
Measure Description:
Implementation of a car-sharing program allows people to have on-demand access to a shared fleet of
vehicles on an as-needed basis. VMT reduction occurs due to reductions in private vehicle ownership,
lower convenience associated with indirect vehicle access, and the transparent cost of vehicle use. User
costs are typically determined through mileage or hourly rates, with deposits and/or annual membership
fees. The car-sharing program could be created through a local partnership or through one of many
existing car-share companies. Car-sharing programs may be grouped into three general categories:
residential- or citywide-based, employer-based, and transit station-based. Transit station-based programs
focus on providing the “last-mile” solution and link transit with commuters’ final destinations. Residential-
based programs work to substitute entire household-based trips. Employer-based programs provide a
means for business/day trips for alternative mode commuters and provide a guaranteed ride home option
(CAPCOA 2010, p. 245).
Measure Applicability:
Urban and suburban context
Negligible in a rural context
Appropriate for residential, retail, office, industrial, and mixed-use projects
Inputs:
The following information needs to be provided by the project applicant:
% reduction in car share member annual VMT
Number of car share members per household
Mitigation Method:
% 𝑅𝐿𝑅 𝑅𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖=𝑃𝐶𝑎𝑟𝑆�𝑎𝑟𝑐× 𝐴𝑎𝑖𝑖𝑖𝑖𝑖𝑖 𝑅𝑎𝑖𝑎
Where:
𝑃𝐶𝑎𝑟𝑆�𝑎𝑟𝑐=% 𝑖𝑎𝑎𝑖𝑎𝑖𝑖𝑖𝑖 𝑖𝑖 𝑎𝑎𝑖 𝑖ℎ𝑎𝑖𝑎 𝑖𝑎𝑖𝑎𝑎𝑖 𝑎𝑖𝑖𝑖𝑎𝑖 𝑅𝐿𝑅
𝐴𝑎𝑖𝑖𝑖𝑖𝑖𝑖 𝑅𝑎𝑖𝑎=𝑖𝑖𝑖𝑎𝑎𝑖 𝑖𝑎 𝑎𝑎𝑖 𝑖ℎ𝑎𝑖𝑎 𝑖𝑎𝑖𝑎𝑎𝑖𝑖 𝑖𝑎𝑖 ℎ𝑖𝑖𝑖𝑎ℎ𝑖𝑖𝑎
Detail:
𝑃𝐶𝑎𝑟𝑆�𝑎𝑟𝑐=26.9 𝑖𝑖 37%
𝐴𝑎𝑖𝑖𝑖𝑖𝑖𝑖 𝑅𝑎𝑖𝑎=1% 𝑖𝑖 2%
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Discussion:
The applicant must consider the demand for car-shares in a community before calculating a VMT
reduction. If a community cannot support the proposed number of cars deployed, VMT reduction may be
overestimated.
The percent reduction in car share member annual VMT is dependent on characteristics of the
community, its residents, and for what purposes the car-sharing program is to be used for. Analysts
should consult the literature to understand how these variables affect the range of reductions prior to
completing the calculation of VMT reduction.
References:
Clewlow, Regina R. and Mishra, Gouri Shankar, (2017). Disruptive Transportation: The Adoption,
Utilization, and Impacts of Ride-Hailing in the United States. UC Davis, Institute of Transportation Studies.
Research Report - UCD-ITS-RR-17-07.
Lovejoy, K. et al. (2013). Impacts of Carsharing on Passenger Vehicle Use and Greenhouse Gas Emissions -
Policy Brief and Technical Background Document. California Air Resources Board. Retrieved from:
https://arb.ca.gov/cc/sb375/policies/policies.htm
Quantifying Greenhouse Gas Mitigation Measures, California Air Pollution Control Officers Association
(CAPCOA), 2010. Chapter 3.4.9 Implement Car-Sharing Program
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CAPCOA Guidance on Combining TDM
Strategies
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Chapter 6 55 Transportation Measures (Five Subcategories) Global Maximum Reduction (all VMT): urban = 75%; compact infill = 40%; suburban center or suburban with NEV = 20%; suburban = 15% Global Cap for Road Pricing needs further study Transportation Measures (Four Categories) Cross-Category Max Reduction (all VMT): urban = 70%; compact infill = 35%; suburban center or suburban with NEV = 15%; suburban = 10% Max Reduction = 15% overall; work VMT = 25%; school VMT = 65%; Max Reduction = 25% (all VMT) Land Use / Location Neighborhood / Site Enhancement Parking Policy / Pricing Transit System Improvements Commute Trip Reduction (assumes mixed use) Road Pricing Management Vehicles Max Reduction: urban = 65%; compact infill = 30%; suburban center = 10%; suburban = 5% Max Reduction: without NEV = 5%; with NEV = 15% Max Reduction = 20% Max Reduction = 10% Max Reduction = 25% Max Reduction = 25% (work VMT) Density (30%) Pedestrian Network (2%) Parking Supply Limits (12.5%) Network Expansion (8.2%) CTR Program Required = 21% work VMT Voluntary = 6.2% work VMT Cordon Pricing (22%) Electrify Loading Docks Design (21.3%) Traffic Calming (1%) Unbundled Parking Costs (13%) Service Frequency / Speed (2.5%) Transit Fare Subsidy (20% work VMT) Traffic Flow Improvements (45% CO2) Utilize Alternative Fueled Vehicles Location Efficiency (65%) NEV Network (14.4) <NEV Parking> On-Street Market Pricing (5.5%) Bus Rapid Transit (3.2%) Employee Parking Cash-out (7.7% work VMT) Required Contributions by Project Utilize Electric or Hybrid Vehicles Diversity (30%) Car Share Program (0.7%) Residential Area Parking Permits Access Improvements Workplace Parking Pricing (19.7% work VMT) Destination Accessibility (20%) Bicycle Network <Lanes> <Parking> <Land Dedication for Trails> Station Bike Parking Alternative Work Schedules & Telecommute (5.5% work VMT) Transit Accessibility (25%) Urban Non-Motorized Zones Local Shuttles CTR Marketing (5.5% work VMT) BMR Housing (1.2%) Park & Ride Lots* Employer-Sponsored Vanpool/Shuttle (13.4% work VMT) Orientation Toward Non-Auto Corridor Ride Share Program (15% work VMT) Proximity to Bike Path Bike Share Program End of Trip Facilities Note: Strategies in bold text are primary strategies with reported VMT reductions; non-bolded strategies are support or grouped strategies. Preferential Parking Permit School Pool (15.8% school VMT) School Bus (6.3% school VMT) Chart 6-2: Transportation Strategies Organization 1-100DocuSign Envelope ID: 6DCFEAC2-FD58-4899-9F45-7A7FDDCD8D92
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Grouping of Strategies
Strategies noted as “grouped” are separately documented in individual Fact Sheets but must
be paired with other strategies within the category. When these “grouped” strategies are
implemented together, the combination will result in either an enhancement to the primary
strategy by improving its effectiveness or a non-negligible reduction in effectiveness that would
not occur without the combination.
Rules for Combining Strategies or Measures
Mitigation measures or strategies are frequently implemented together with other measures.
Often, combining measures can lead to better emission reductions than implementing a single
measure by itself. Unfortunately, the effects of combining the measures are not always as
straightforward as they might at first appear. When more and more measures are
implemented to mitigate a particular source of emissions, the benefit of each additional
measure diminishes. If it didn’t, some odd results would occur. For example, if there were a
series of measures that each, independently, was predicted to reduce emissions from a source
by 10%, and if the effect of each measure was independent of the others, then implementing
ten measures would reduce all of the emissions; and what would happen with the eleventh
measure? Would the combination reduce 110% of the emissions? No. In fact, each
successive measure is slightly less effective than predicted when implemented on its own.
On the other hand, some measures enhance the performance of a primary measure when they
are combined. This Report includes a set of rules that govern different ways of combining
measures. The rules depend on whether the measures are in the same category, or different
categories. Remember, the categories include: Energy, Transportation, Water, Landscape
Equipment, Solid Waste, Vegetation, Construction, Miscellaneous Categories, and General
Plans.
Combinations Between Categories: The following procedures must be followed when
combining mitigation measures that fall in separate categories. In order to determine the
overall reduction in GHG emissions compared to the baseline emissions, the relative
magnitude of emissions between the source categories needs to be considered. To do this,
the user should determine the percent contribution made by each individual category to the
overall baseline GHG emissions. This percent contribution by a category should be multiplied
by the reduction percentages from mitigation measures in that category to determine the
scaled GHG emission reductions from the measures in that category. This is done for each
category to be combined. The scaled GHG emissions for each category can then be added
together to give a total GHG reduction for the combined measures in all of the categories.
For example, consider a project whose total GHG emissions come from the following
categories: transportation (50%), building energy use (40%), water (6%), and other (4%). This
project implements a transportation mitigation measure that results in a 10% reduction in VMT.
The project also implements mitigation measures that result in a 30% reduction in water
usage. The overall reduction in GHG emissions is as follows:
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Reduction from Transportation: 0.50 x 0.10 = 0.5 or 5%
Reduction from Water: 0.06 x 0.30 = 0.018 or 1.8%
Total Reduction: 5% + 1.8% = 6.8%
This example illustrates the importance of the magnitude of a source category and its influence
on the overall GHG emission reductions.
The percent contributions from source categories will vary from project to project. In a
commercial-only project it may not be unusual for transportation emissions to represent greater
than 75% of all GHG emissions whereas for a residential or mixed use project, transportation
emissions would be below 50%.
Combinations Within Categories: The following procedures must be followed when
combining mitigation measures that fall within the same category.
Non-Transportation Combinations: When combining non-transportation subcategories, the
total amount of reductions for that category should not exceed 100% except for categories that
would result in additional excess capacity that can be used by others, but which the project
wants to take credit for (subject to approval of the reviewing agency). This may include
alternative energy generation systems tied into the grid, vegetation measures, and excess
graywater or recycled water generated by the project and used by others. These excess
emission reductions may be used to offset other categories of emissions, with approval of the
agency reviewing the project. In these cases of excess capacity, the quantified amounts of
excess emissions must be carefully verified to ensure that any credit allowed for these
additional reductions is truly surplus.
Category Maximum- Each category has a maximum allowable reduction for the
combination of measures in that category. It is intended to ensure that emissions are not
double counted when measures within the category are combined. Effectiveness levels for
multiple strategies within a subcategory (as denoted by a column in the appropriate chart,
above) may be multiplied to determine a combined effectiveness level up to a maximum
level. This should be done first to mitigation measures that are a source reduction followed
by those that are a reduction to emission factors. Since the combination of mitigation
measures and independence of mitigation measures are both complicated, this Report
recommends that mitigation measure reductions within a category be multiplied unless a
project applicant can provide substantial evidence indicating that emission reductions are
independent of one another. This will take the following form:
GHG emission reduction for category = 1-[(1-A) x (1-B) x (1-C)]
Where:
A, B and C = Individual mitigation measure reduction percentages for the strategies to be
combined in a given category.
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Global Maximum- A separate maximum, referred to as a global maximum level, is also
provided for a combination across subcategories. Effectiveness levels for multiple
strategies across categories may also be multiplied to determine a combined effectiveness
level up to global maximum level.
For example, consider a project that is combining 3 mitigation strategies from the water
category. This project will install low-flow fixtures (measure WUW-1), use water-efficient
irrigation (measure WUW-4, and reduce turf (measure WUW-5). Reductions from these
measures will be:
x low-flow fixtures 20% or 0.20 (A)
x water efficient irrigation 10% or 0.10 (B)
x turf reductions 20% or 0.20 (C)
To combine measures within a category, the reductions would be
= 1-[(1-A) x (1-B) x (1-C)]
= 1-[(1-.20) x (1-.10) x (1-.20)]
= 1-[(0.8) x (0.9) x (.8)]
= 1-0.576 = 0.424
= 42.4%
Transportation Combinations: The interactions between the various categories of
transportation-related mitigation measures is complex and sometimes counter-intuitive.
Combining these measures can have a substantive impact on the quantification of the
associated emission reductions. In order to safeguard the accuracy and reliability of the
methods, while maintaining their ease of use, the following rules have been developed and
should be followed when combining transportation-related mitigation measures. The rules are
presented by sub-category, and reference Chart 6-2 Transportation Strategies Organization.
The maximum reduction values also reflect the highest reduction levels justified by the
literature. The chart indicates maximum reductions for individual mitigation measures just
below the measure name.
Cross-Category Maximum- A cross-category maximum is provided for any combination of
land use, neighborhood enhancements, parking, and transit strategies (columns A-D in
Chart 6-1, with the maximum shown in the top row). The total project VMT reduction
across these categories should be capped at these levels based on empirical evidence.3
Caps are provided for the location/development type of the project. VMT reductions may
be multiplied across the four categories up to this maximum. These include:
x Urban: 70% VMT
x Compact Infill: 35%
x Suburban Center (or Suburban with NEV): 15%
x Suburban: 10% (note that projects with this level of reduction must include a diverse
land use mix, workforce housing, and project-specific transit; limited empirical
evidence is available)
(See blue box, pp. 58-59.)
3 As reported by Holtzclaw, et al for the State of California.
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As used in this Report, location settings are defined as follows:
Urban: A project located within the central city and may be characterized by multi-family housing, located near office and retail. Downtown
Oakland and the Nob Hill neighborhood in San Francisco are examples of the typical urban area represented in this category. The urban
maximum reduction is derived from the average of the percentage difference in per capita VMT versus the California statewide average
(assumed analogous to an ITE baseline) for the following locations:
Location Percent Reduction from Statewide
VMT/Capita
Central Berkeley -48%
San Francisco -49%
Pacific Heights (SF) -79%
North Beach (SF) -82%
Mission District (SF) -75%
Nob Hill (SF) -63%
Downtown Oakland -61%
The average reflects a range of 48% less VMT/capita (Central Berkeley) to 82% less VMT/capita (North Beach, San Francisco) compared
to the statewide average. The urban locations listed above have the following characteristics:
o Location relative to the regional core: these locations are within the CBD or less than five miles from the CBD (downtown Oakland and
downtown San Francisco).
o Ratio or relationship between jobs and housing: jobs-rich (jobs/housing ratio greater than 1.5)
o Density character
x typical building heights in stories: six stories or (much) higher
x typical street pattern: grid
x typical setbacks: minimal
x parking supply: constrained on and off street
x parking prices: high to the highest in the region
o Transit availability: high quality rail service and/or comprehensive bus service at 10 minute headways or less in peak hours
Compact infill: A project located on an existing site within the central city or inner-ring suburb with high-frequency transit service.
Examples may be community redevelopment areas, reusing abandoned sites, intensification of land use at established transit stations, or
converting underutilized or older industrial buildings. Albany and the Fairfax area of Los Angeles are examples of typical compact infill area
as used here. The compact infill maximum reduction is derived from the average of the percentage difference in per capita VMT versus the
California statewide average for the following locations:
Location Percent Reduction from Statewide
VMT/Capita
Franklin Park, Hollywood -22%
Albany -25%
Fairfax Area, Los Angeles -29%
Hayward -42%
The average reflects a range of 22% less VMT/capita (Franklin Park, Hollywood) to 42% less VMT/capita (Hayward) compared to the
statewide average. The compact infill locations listed above have the following characteristics:
o Location relative to the regional core: these locations are typically 5 to 15 miles outside a regional CBD
o Ratio or relationship between jobs and housing: balanced (jobs/housing ratio ranging from 0.9 to 1.2)
o Density character
x typical building heights in stories: two to four stories
x typical street pattern: grid
x typical setbacks: 0 to 20 feet
x parking supply: constrained
x parking prices: low to moderate
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Global Maximum- A global maximum is provided for any combination of land use,
neighborhood enhancements, parking, transit, and commute trip reduction strategies (the
first five columns in the organization chart). This excludes reductions from road-pricing
measurements which are discussed separately below. The total project VMT reduction
across these categories, which can be combined through multiplication, should be capped
As used in this Report, additional location settings are defined as follows:
Suburban Center: A project typically involving a cluster of multi-use development within dispersed, low-density, automobile dependent
land use patterns (a suburb). The center may be an historic downtown of a smaller community that has become surrounded by its region’s
suburban growth pattern in the latter half of the 20th Century. The suburban center serves the population of the suburb with office, retail
and housing which is denser than the surrounding suburb. The suburban center maximum reduction is derived from the average of the
percentage difference in per capita VMT versus the California statewide average for the following locations:
Location Percent Reduction from
Statewide VMT/Capita
Sebastopol 0%
San Rafael (Downtown) -10%
San Mateo -17%
The average reflects a range of 0% less VMT/capita (Sebastopol) to 17% less VMT/capita (San Mateo) compared to the statewide
average. The suburban center locations listed above have the following characteristics:
o Location relative to the regional core: these locations are typically 20 miles or more from a regional CBD
o Ratio or relationship between jobs and housing: balanced
o Density character
x typical building heights in stories: two stories
x typical street pattern: grid
x typical setbacks: 0 to 20 feet
x parking supply: somewhat constrained on street; typically ample off-street
x parking prices: low (if priced at all)
o Transit availability: bus service at 20-30 minute headways and/or a commuter rail station
While all three locations in this category reflect a suburban “downtown,” San Mateo is served by regional rail (Caltrain) and the other
locations are served by bus transit only. Sebastopol is located more than 50 miles from downtown San Francisco, the nearest urban
center. San Rafael and San Mateo are located 20 miles from downtown San Francisco.
Suburban: A project characterized by dispersed, low-density, single-use, automobile dependent land use patterns, usually outside of the
central city (a suburb). Suburbs typically have the following characteristics:
o Location relative to the regional core: these locations are typically 20 miles or more from a regional CBD
o Ratio or relationship between jobs and housing: jobs poor
o Density character
x typical building heights in stories: one to two stories
x typical street pattern: curvilinear (cul-de-sac based)
x typical setbacks: parking is generally placed between the street and office or retail buildings; large-lot residential is common
x parking supply: ample, largely surface lot-based
x parking prices: none
o Transit availability: limited bus service, with peak headways 30 minutes or more
The maximum reduction provided for this category assumes that regardless of the measures implemented, the project’s distance from
transit, density, design, and lack of mixed use destinations will keep the effect of any strategies to a minimum.
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at these levels based on empirical evidence.4 Maximums are provided for the
location/development type of the project. The Global Maximum values can be found in the
top row of Chart 6-2.
These include:
x Urban: 75% VMT
x Compact Infill: 40% VMT
x Suburban Center (or Suburban with NEV): 20%
x Suburban: 15% (limited empirical evidence available)
Specific Rules for Subcategories within Transportation- Because of the unique interactions
of measures within the Transportation Category, each subcategory has additional rules or
criteria for combining measures.
Land Use/Location Strategies – Maximum Reduction Factors: Land use measures apply
to a project area with a radius of ½ mile. If the project area under review is greater than
this, the study area should be divided into subareas of radii of ½ mile, with subarea
boundaries determined by natural “clusters” of integrated land uses within a common
walkshed. If the project study area is smaller than ½ mile in radius, other land uses
within a ½ mile radius of the key destination point in the study area (i.e. train station or
employment center) should be included in design, density, and diversity calculations.
Land use measures are capped based on empirical evidence for location setting types
as follows:5
x Urban: 65% VMT
x Compact Infill: 30% VMT
x Suburban Center: 10% VMT
x Suburban: 5% VMT
Neighborhood/Site Enhancements Strategies – Maximum Reduction Factors: The
neighborhood/site enhancements category is capped at 12.7% VMT reduction (with
Neighborhood Electric Vehicles (NEVs)) and 5% without NEVs based on empirical
evidence (for NEVs) and the multiplied combination of the non-NEV measures.
Parking Strategies – Maximum Reduction Factors: Parking strategies should be
implemented in one of two combinations:
x Limited (reduced) off-street supply ratios plus residential permit parking and
priced on-street parking (to limit spillover), or
x Unbundled parking plus residential permit parking and priced on-street
parking (to limit spillover).
4 As reported by Holtzclaw, et al for the State of California. Note that CTR strategies must be converted to overall VMT
reductions (from work-trip VMT reductions) before being combined with strategies in other categories. 5 As reported for California locations in Holtzclaw, et al. “Location Efficiency: Neighborhood and Socioeconomic
Characteristics Determine Auto Ownership and Use – Studies in Chicago, Los Angeles, and San Francisco.” Transportation
Planning and Technology, 2002, Vol. 25, pp. 1–27.
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Note: The reduction maximum of 20% VMT reflects the combined (multiplied)
effect of unbundled parking and priced on-street parking.
Transit System Strategies – Maximum Reduction Factors: The 10% VMT reduction
maximum for transit system improvements reflects the combined (multiplied) effect
of network expansion and service frequency/speed enhancements. A
comprehensive transit improvement would receive this type of reduction, as shown
in the center overlap in the Venn diagram, below.
Commuter Trip Reductions (CTR) Strategies – Maximum Reduction Factors: The
most effective commute trip reduction measures combine incentives, disincentives,
and mandatory monitoring, often through a transportation demand management
(TDM) ordinance. Incentives encourage a particular action, for example parking
cash-out, where the employee receives a monetary incentive for not driving to work,
but is not punished for maintaining status quo. Disincentives establish a penalty for
a status quo action. An example is workplace parking pricing, where the employee
is now monetarily penalized for driving to work. The 25% maximum for work-related
VMT applies to comprehensive CTR programs. TDM strategies that include only
incentives, only disincentives, and/or no mandatory monitoring, should have a lower
total VMT reduction than those with a comprehensive approach. Support strategies
to strengthen CTR programs include guaranteed-ride-home, taxi vouchers, and
message boards/marketing materials. A 25% reduction in work-related VMT is
assumed equivalent to a 15% reduction in overall project VMT for the purpose of the
global maximum; this can be adjusted for project-specific land use mixes.
Two school-related VMT reduction measures are also provided in this category. The
maximum reduction for these measures should be 65% of school-related VMT
based on the literature.
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Road Pricing/Management Strategies – Maximum Reduction Factors: Cordon
pricing is the only strategy in this category with an expected VMT reduction potential.
Other forms of road pricing would be applied at a corridor or region-wide level rather
than as mitigation applied to an individual development project. No domestic case
studies are available for cordon pricing, but international studies suggest a VMT
reduction maximum of 25%. A separate, detailed, and project-specific study should
be conducted for any project where road pricing is proposed as a VMT reduction
measure.
Additional Rules for Transportation Measures- There are also restrictions on the
application of measures in rural applications, and application to baseline, as follows:
Rural Application: Few empirical studies are available to suggest appropriate VMT
reduction caps for strategies implemented in rural areas. Strategies likely to have
the largest VMT reduction in rural areas include vanpools, telecommute or
alternative work schedules, and master planned communities (with design and land
use diversity to encourage intra-community travel). NEV networks may also be
appropriate for larger scale developments. Because of the limited empirical data in
the rural context, project-specific VMT reduction estimates should be calculated.
Baseline Application: As discussed in previous sections of this report, VMT
reductions should be applied to a baseline VMT expected for the project, based on
the Institute of Transportation Engineers’ 8th Edition Trip Generation Manual and
associated typical trip distance for each land use type. Where trip generation rates
and project VMT provided by the project Applicant are derived from another source,
the VMT reductions must be adjusted to reflect any “discounts” already applied.
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