HomeMy WebLinkAbout2025-09-25; Vehicles Miles Traveled Screening Criteria Update {Districts -All); Barberio, GaryTo the members of the:
I COUNCIL
Date '\ 2S 2.5cA ✓ cc ✓ v
C ACM ./ DCM (3) _ --
Council Memorandum
September 25, 2025
To:
From:
Honorable Mayor Blackburn and Members of the City Council
Gary Barberio, Deputy City Manager, Community Services
Jeff Murphy, Community Development Director
Via:
Re:
Sheila Cobian, Assistant City Manager '):;~
Vehicles Miles Traveled Screening Criteria Update {Districts -All)
{city of
Carlsbad
Memo ID# 2025058
This memorandum provides an update to the city's use of certain Vehicle Miles Traveled screening
criteria, which is a tool applied to new development projects when assessing transportation impacts
under the California Environmental Quality Act (CEQA).
Background
Senate Bill 743, adopted in 2013, led to a significant change in the way transportation impacts are
measured under CEQA. The bill mandated that jurisdictions can no longer use automobile delay -
commonly measured by Level of Service (LOS) -as the performance measure to determine the
transportation impacts of land development projects pursuant to CEQA. Rather, the state developed
an alternative standard, called Vehicle Miles Traveled or VMT. In short, VMT is a metric that measures
the total distance driven by all vehicles in a specific area over a set period, accounting for both the
number of vehicle trips and their lengths. Basically, LOS measures traffic congestion, while VMT
measures travel distance.
As part of the methodology for measuring VMT impacts, the state developed sample screening criteria
that public agencies could use to quickly and easily screen out projects that are likely not to cause
significant environmental impacts. In other words, development projects meeting the screening
criteria do not need to provide any additional analysis or assessments on project related VMT impacts.
The City Council considered and adopted the city's VMT screening criteria and thresholds for
determining significant on June 16, 2020 (Attachment A). An Informational Bulletin on VMT was
subsequently developed and is currently available on the city's website (Attachment C).
Discussion
The following is an update on the city's application of certain VMT screening criteria since the City
Council's action in 2020.
Modification of Certain Screening Criteria
As noted above, the state (specifically, the Governor's Office of Land Use and Climate Innovation),
published a technical advisory regarding appropriate thresholds for screening out VMT impacts. The
County of San Diego adopted the VMT screening thresholds from the technical advisory, two of which
Community Services Branch
Community Development Department
1635 Faraday Avenue I Carlsbad, CA 92008 I 442-339-2600 t
Council Memo -Vehicles Miles Traveled Screening Criteria Update (Districts -All)
September 25, 2025
Page 2
allowed the county to screen out projects in designated infill areas located near transit ("transit
proximate projects") and smaller projects expected to generate no more than 110 automobile trips per
day ("small development projects"). The City of Carlsbad, like most cities, adopted the same screening
thresholds described in the technical advisory, including these two.
Environmental groups sued the county over its use of the two thresholds arguing, in part, that these
thresholds lacked supporting evidence based on local conditions. The court of appeal agreed,
concluding that a local agency must determine, based on substantial evidence, the VMT screening
criteria it elects to use are locally suited to the purpose of identifying VMT impacts ---this analysis
must be conducted irrespective of the screenings origin, even if they are recommended by the
Governor's Office of Land Use and Climate Innovation.
Accordingly, the Court of Appeal's decision invalidated the county's use of these two screening
thresholds. The county subsequently requested further review but on July 16, 2025, the California
Supreme Court denied the county's petition for review, rendering the appellate court district's decision
final. This means that if the City of Carlsbad is challenged on this issue a trial court is required to follow
the Court of Appeals decision.
Consequently, the Community Development Department has reviewed the screening criteria
considering the recent appellate court decision and how the ruling might impact projects at various
stages of planning or construction. Based on this review, the Community Development Department
developed a process for processing projects involving the "transit proximate project" and "small
project" screening criteria, which was outlined in a letter to the Building Industry Association
(Attachment B). In short, applicants are still able to use the two screening thresholds but must provide
substantial evidence proving that the screening threshold is applicable and appropriate to their
project. This substantial evidence shall be made part of the project record and subject to public review
and comment.
Update to the VMT Analysis Map
VMT analysis maps are a tool used by most jurisdictions to determine whether a project is located
within an area where it will result in a significant impact on the environment due to VMT impacts. But
unlike the two screening criteria discussed in the previous section, these maps are developed using
regional transportation modeling that relies on the best available local transportation data ---namely,
data developed and maintained by the San Diego Association of Governments (SAN DAG) and Caltrans.
As such, VMT analysis maps remain a valid tool for the purpose of identifying local VMT impacts.
Additional information on the value of these maps is discussed in the Community Development
Department's Informational Bulletin (Attachment C).
The resulting maps from this modeling show three color intensities: Green color represents areas in
the city where projects are expected to have a less than significant VMT impact and therefore no
further VMT analysis is required (i.e., areas in the city where the model shows that development, for
VMT purposes, should be located); medium blue color represents areas that are likely to have a
significant VMT impact, but one that could potentially be mitigated with VMT reducing measures to a
Council Memo -Vehicles Miles Traveled Screening Criteria Update (Districts -All)
September 25, 2025
Page 3
level of less than significant (i.e., areas in the city where the model shows that development, for VMT
purposes, is not ideally situated, but the impacts could be mitigated through measures such as those
identified in the city's Transportation Demand Management Plan); and, darkest blue color represent
areas that are likely to have a significant VMT impact and are unlikely to fully mitigate that impact (i.e.,
areas where the model shows that development, for VMT purposes, are not preferred and a full
Environmental Impact Report may be required to analyze the magnitude of the impacts.
The SAN DAG model is typically updated every four years to coincide with adoption of the SAN DAG
Regional Plan/Regional Transportation Plan (RTP). SAN DAG is finalizing its 2026 RTP and staff anticipate
that updated VMT modeling will be available sometime in Summer 2026. Since changes in land use
assumptions impact the mapping of VMT priority zones, staff has updated its VMT Analysis Maps
(Attachment D) ahead of schedule to account for the additional planned housing development that
was approved with the adoption of the Housing Element rezone program.
Next Steps
The updated VMT maps will be posted on the city's website. The maps will be updated again once
SAN DAG approves the 2026 RTP and they release the updated Regional Travel Demand Model Activity
Based Model.
Attachments:
A. City Council staff report, dated June 16, 2020 (on file with the City Clerk's Office)
B. City letter to BIA dated May 21, 2025
C. Informational Bulletin IB-160
D. VMT Analysis Maps
cc: Geoff Patnoe, City Manager
Cindie McMahon, City Attorney
Dalton Sorich, Assistant City Attorney
Tom Frank, Transportation Director/City Engineer
Nathan Schmidt, Transportation Planning & Mobility Manager
Mike Strong, Assistant Director of Community Development
Eric Lardy, City Planner
Robert Efird Ill, Principal Planner
Jason Geldert, Engineering Manager
Tim Carroll, Principal Engineer
Nicole Fine, Senior Engineer
May 21, 2025
Ms. Lori Holt Pfeiler, President & CEO
Building Industry Association of San Diego County
Lori@biasandiego.org
Vehicle Miles Travelled (VMT) Screening Criteria & Thresholds
Dear Ms. Pfeiler:
Attachment B
(city of
Carlsbad
VIA EMAIL ONLY
The City of Carlsbad is in receipt of your letter dated May 13, 2025, regarding the city's
discontinuance of the "small projects" and "near transit" screening criteria from its Vehicle
Miles Traveled (VMT) thresholds. This letter is intended to respond to your assertion that the
city's action in this case was "unnecessary, and procedurally and legally improper."
By way of background, State CEQA Guidelines allow public agencies to adopt thresholds of
significance to determine when an impact from a proposed project does not require
environmental review. The Governor's Office of Land Use and Climate Innovation (LUCI),
formerly the Office of Planning and Research, published a technical advisory regarding
appropriate thresholds for screening out VMT impacts. Like the County of San Diego, and
virtually every other city in the region, the City of Carlsbad adopted on June 16, 2020, two VMT
thresholds from the technical advisory. The thresholds allowed the city to screen out projects in
designated infill areas likely to be provided with transit in the future and small projects
expected to generate no more than 110 automobile trips per day.
The Cleveland National Forest Foundation recently sued the County of San Diego over its use of
these two thresholds arguing, in part, that these thresholds lacked supporting evidence based
on local conditions. The court of appeal agreed with the lower court's determination,
concluding a local agency cannot use another agency's screening threshold absent substantial
evidence the threshold and underlying assumptions are valid and applicable to local conditions.
Accordingly, the court of appeal's decision invalidates the county's use of these two screening
thresholds.
The city disagrees with your assertion that the court's ruling is limited to the unincorporated
area of San Diego County because the City of Carlsbad was not specifically named in the
lawsuit. Unlike in the federal court system, in the state court system all published appellate
court decisions are binding and set a precedent that all lower courts must follow in similar
future cases.
For the case in question, the appellate court concluded that each lead agency, which would
include Carlsbad, must determine, based on fact-based substantial evidence, that the VMT
significance thresholds it elects to use (regardless of their origin) are locally suited to the
Community Development Department
1635 Faraday Avenue I Carlsbad, CA 92008 I 760-602-2710 t
Ms. Lori Holt Pfeiler
May 21, 2025
Page 2
purpose of identifying VMT impacts. While the County of San Diego has petitioned to have the
California Supreme Court review the case, there is no assurance the California Supreme Court
will grant the petition or stay the court of appeal's decision in the interim.
Should the city continue to apply the two VMT thresholds to development projects while the
county pursues its judicial remedies, applicants actively processing applications for
development projects assume liability risks and time delays should the county be unsuccessful.
The city also faces liability risks in doing so.
Consequently, to be prudent, the Community Development Department has reviewed the
screening thresholds considering this court decision and has identified how the ruling might
impact projects at various stages of planning or construction. Based on this review, the
Community Development Department has developed the following interim process for
processing projects until the concerns regarding the "small projects" and "near transit"
screening criteria are resolved:
• Projects under construction. All projects under construction may continue under
current approvals until completion of the project, including all the remaining phases and
tenant improvements as shown on the approved plans.
• Projects approved. A CEQA decision is final unless subsequent discretionary approval is
required. All projects currently in grading or building plan check may continue to be
reviewed under current approvals.
• Projects under review. If a CEQA decision has not been made by a final decision-maker,
then applicant will need to supplement their CEQA analysis if they were/are relying on
the "small projects" and "near transit" screening criteria. Supplemental information may
include but is not limited to local VMT modeling and analysis of whether such projects
would result in an impact. Alternatively, applicants may use one of the other screening
criteria that was not challenged, including: (1) "local-serving retail," (2) "local-serving
public facility," (3) "affordable housing project," and (4) "redevelopment resulting in a
net reduction of VMT." Projects may also be located in areas where VMT is already
below the 15% standard ("low-VMT threshold") which would result in a less-than-
significant VMT impact. Additional VMT analysis may be needed only if the project is not
otherwise exempt from environmental review and will be located in an area where per
capita VMT is above the 15% standard, i.e., where the transportation effect is
potentially significant.
• All other projects. For projects not screened out of VMT analysis, the determination of
whether a project may have a significant effect on VMT must be based to the extent
possible on scientific and factual data.
The department does not anticipate bringing forward any amendments to its VMT thresholds
for City Council consideration until the county exhausts its legal remedies. Until then, the
department shall continue to apply the process described above. We understand that other
Ms. Lori Holt Pfeiler
May 21, 2025
Page 3
surrounding jurisdictions are also applying the same or similar approach to this issue as the City
of Carlsbad.
We are happy to meet with you should you have any questions or wish to meet to discuss
further.
RPHY, Director
Community Development Department
Attachment: BIA Letter dated May 13, 2025
cc: Geoff Patnoe, City Manager
Sheila Cobain, Assistant City Manager
Gary Barberio, Deputy City Manager
Cindie McMahon, City Attorney
Dalton Sorich, Assistant City Attorney
Mike Strong, Assistant Director
Eric Lardy, City Planner
Caylin Frank, BIA Legislative Affairs & Outreach Manager (caylin@biasandiego.org)
Community Development Department | 1635 Faraday Ave. | Carlsbad, CA 92008 | www.carlsbadca.gov
Vehicle Miles Traveled IB-160
This info-bulletin summarizes the process of analyzing
and mitigating transportation impacts resulting from
development projects using the Vehicle Miles
Traveled (VMT) methodology, as required under the
California Environmental Quality Act (CEQA). The
intent of this bulletin is to provide the public with a
high-level understanding of VMT; it is not intended to
act as a technical guide.
SENATE BILL 743
SB 743 (Public Resources Code §21099) was passed
by the state legislature and signed into law in the fall
of 2013 and led to a significant change in the way
transportation impacts are measured under CEQA.
Refer to IB-150 for more information on CEQA. SB 743
mandates that jurisdictions can no longer use
automobile delay – commonly measured by Level of
Service (LOS) – as the performance measure to
determine the transportation impacts of land
development projects pursuant to CEQA.
While a replacement performance measure was not
specified, SB 743 required that the replacement
metric needed to bring CEQA transportation analyses
into closer alignment with other statewide policies
regarding greenhouse gas reductions, smart growth,
and improved and expanded multimodal
transportation networks (e.g., more complete streets
to serve a variety of roadway users including
pedestrians and bicyclists).
LAND USE & CLIMATE INNOVATION
One of the primary responsibilities of the Governor’s
Office of Land Use & Climate Innovation (LCI),
previously known as the Office of Planning & Research
or OPR, is to update and develop new guidelines and
technical advice to assist jurisdiction in the application
of CEQA. These “advisories” provide general advice
and recommendations, which agencies, the public,
and other entities may use at their discretion. For
more information on the role of LCI in CEQA, refer to
IB-150.
SB 743 designated LCI to develop detailed
implementation guidelines consistent with state law
that jurisdictions could use for CEQA transportation
analysis. While the bill does not prevent jurisdictions
from developing their own methodologies or
guidelines, the city, along with virtually every other
jurisdiction in the state, opted to follow state
guidance.
When developing a replacement for LOS, the state
looked towards an alternative transportation impact
metric that more closely approximates the true
environmental impacts of driving --- how much actual
auto travel (additional miles driven) a proposed
project would create on regional and local roads. If
the project adds excessive car travel onto our roads,
the project may cause a significant transportation
impact that requires mitigation under CEQA.
The process of writing guidelines started in January
2014 and concluded in 2018, when the state released
their guidance document entitled Technical Advisory
on Evaluating Transportation Impacts in CEQA
Documents Referenced
Senate Bill 743; PRC §21099
LCI (OPR) Technical Advisory; Technical Advisory
CAPCOA Guidance Document; GHG Handbook
Carlsbad VMT Analysis Guidelines; VMT Guidelines
VMT Analysis Maps: Maps
Transportation Demand Management Program; TDM
CEQA Informational Bulletin; IB-150
Attachment C
CA Governors Office of
Land Use and
Climate Innovation
{city of
Carlsbad
Informational Bulletin
Page 2 of 8 IB-160_Vehicle Miles Traveled_September 2025
(Technical Advisory), which cities can, and have used
to develop their own VMT guidelines. The Technical
Advisory contains technical recommendations
regarding assessment of VMT, thresholds of
significance, screening criteria, and mitigation
guidance. More on this below.
CALIFORNIA NATURAL RESOURCES AGENCY
The mission of the California Natural Resources
Agency (Resources Agency) is to restore, protect and manage the state’s natural, historical, and cultural
resources. Among other duties, the Resources Agency
is tasked with updating the state’s CEQA Guidelines,
based on LCI recommendations.
Relative to VMT, the Resources Agency on Dec. 28,
2018 adopted revisions to CEQA Guidelines §15064.3
stating that VMT is the most appropriate measure of
transportation impacts under CEQA. This is the official
action taken by the state that replaced LOS with VMT.
Following this action, and the release of the Technical
Advisory, jurisdictions throughout the state had until
July 1, 2020, to adopt local VMT analysis guidelines for
CEQA analysis.
CALIFORNIA ENVIRONMENTAL QUALITY ACT
Before we can discuss the components of the city’s
VMT Analysis Guidelines, which relied heavily on the
Technical Advisory, it is important to define certain
CEQA terms such as “thresholds of significance” and
“screening criteria” to better understand their roles
and functions when reviewing VMT impacts.
Simply put, CEQA requires government agencies to
inform decision-makers and the public about the
potential environmental impacts of proposed
projects, and to reduce those environmental impacts
to the extent feasible. In practice, however, CEQA is a
complex piece of legislation with complicated
processes and procedures that projects must follow.
The sections below provide a brief description of the
aforementioned terms, and how they relate to VMT.
For additional information on how CEQA works,
please refer to our Info-Bulletin IB-150.
CEQA Thresholds of Significance
To assist in determining whether a specific impact is
“significant” under CEQA, public agencies are
encouraged to develop administrative guidance often
referred to as significance thresholds. For VMT
analysis, significance thresholds are based on the use
of land, because land use conditions directly affect transportation activity. For residential projects, LCI
recommends that a project’s VMT per capita be
compared to the citywide average. For office and
industrial projects, a project’s VMT per employee is
compared to the regional average. For retail and other
projects that evaluate VMT, the threshold is based on
the change in VMT in the affected area.
CEQA Screening Criteria
In another method similar to creating significance
thresholds, public agencies are encouraged to develop
“screening criteria” to help quickly and easily screen
out projects that are likely not to cause significant
environmental impacts. For VMT, LCI recommends
that a project may be presumed to not have a
significant impact resulting from VMT if it is near
public transit, comprised entirely of affordable
housing, or considered a small project.
CARLSBAD VMT ANALYSIS GUIDELINES
Transportation impacts and their potential need for
mitigation are important for any community to
consider when contemplating proposed new
developments, expansion of existing developments, or
implementation of transportation projects. Carlsbad
IB-160_Vehicle Miles Traveled_September 2025 Page 3 of 8
residents, businesses, other community members,
and permit decision-makers all have a stake in
understanding and responding to additional demands
on the transportation system.
To help analyze project related transportation
impacts, the city developed VMT Analysis Guidelines
(VMT Guidelines), which include procedures to
promote consistency in VMT analysis and assist with
the evaluation of discretionary projects under CEQA. In preparing and implementing the VMT Guidelines,
the city relied on the Technical Advisory.
The city’s VMT screening criteria and thresholds were
adopted by the City Council on June 16, 2020 (Agenda
Item No. 7). Any changes to the thresholds and
criteria will require City Council action, following
recommendations by the Traffic & Mobility
Commission.
However, the rest of the VMT Guidelines are for
informational purposes only to assist applicants and
their consultants when preparing traffic impact
analyses. As such, with the exception of the screening
criteria and listed thresholds, the VMT Guidelines
themselves may be administratively updated as new
information becomes available.
VMT Screening Criteria
Below are the city’s adopted VMT screening criteria,
which coincide with the VMT screening criteria in the
Technical Advisory with the exception of one, as
reflect in the proceeding table. It is presumed that
projects meeting any one of the criteria listed below will not cause a significant impact on transportation
services. As such, no further VMT analysis or
mitigation is required.
VMT SCREENING CRITERIA
Projects that generate less than 110 average daily
trips1
Residential, office or retail uses located within ½
mile of a major public transit stop or a stop along a
high-quality transit corridor1
Locally serving retail uses (i.e., retail development
that is less than 50,000 square feet in size)
Residential projects made up of entirely affordable
housing
Redevelopment projects that result in a net overall
decrease in VMT for the site
Locally serving public facilities (i.e., public schools,
parks, fire/police stations, libraries, other facilities
intended to serve the local public)2
All screening criteria listed in Technical Advisory for
transportation projects
1 Pursuant to a recent appellate court ruling (Cleveland
National Forest Foundation v. County of San Diego; 2025), the court concluded that a local agency must determine, based on locally developed substantial evidence, the VMT screening criteria it elects to use (regardless of their origin) are locally suited to the purpose of identifying VMT impacts.
Consequently, the Community Development Department has reviewed the screening criteria considering this court decision and developed a process for processing projects involving the
“transit proximate project” and “small project” screening criteria. In short, applicants are still able to use the two
screening thresholds but must provide substantial evidence proving that the screening threshold is applicable and
appropriate to their project. This substantial evidence shall be
made part of the project record and subject to public review
and comment.
2 “Locally serving public facilities” are not specifically defined in
the Technical Advisory. However, like “locally serving retail
uses,” locally serving public facilities redistribute trips rather
than create new ones. For example, the construction of a new
community park or library shortens trips for nearby residents
because users do not need to travel as far to receive the same
public service or benefit. As such, these facilities are screened
out and determined not to have a significant impact on
transportation. It should be noted, however, that if a proposed
public facility includes a use that has the potential of
generating trips from outside the region, such as an
amphitheater or a public golf course, a study evaluating where
users are coming from may be required to demonstrate that a
public facility is locally serving and still eligible to be screened
out under these criteria.
Page 4 of 8 IB-160_Vehicle Miles Traveled_September 2025
VMT Significance Thresholds
A threshold of significance for a given environmental
impact defines the level of effect above which the city
will normally consider impacts to be significant, and
below which it will normally consider impacts to be
less than significant. The table below reflects the City
Council adopted VMT Thresholds of Significance,
which are used to determine whether a project, which
did not meet the screening criteria, will create a
significant transportation impact. The thresholds and
specific VMT metrics used to measure VMT are
described by land use type below. These thresholds
are consistent with Technical Advisory
recommendations. How these thresholds are applied
in practice is discussed later in the bulletin.
PROJECT TYPE THRESHOLD OF SIGNIFICANCE
Residential
A significant transportation impact
occurs if the project VMT/capita
exceeds a level 15% below the city
average VMT/capita.
Office
A significant transportation impact
occurs if the project VMT per
employee exceeds a level 15%
below the regional average
VMT/employee.
Retail
A significant transportation impact
occurs if the project results in a net
increase in VMT.
Industrial
A significant transportation impact
occurs if the project
VMT/employee exceeds the
average regional VMT/employee.
Transportation
A significant transportation impact
occurs if the project creates a net
VMT increase in the affected area.
VMT Analysis Maps
The Technical Advisory advises that a jurisdiction may
use transportation modeling to estimate a project’s
VMT. And CEQA requires that jurisdictions must use
the best available data when assessing project
impacts. As such, jurisdictions, including Carlsbad,
typically use the most current regional travel demand
model available, which is developed and maintained
by the San Diego Association of Governments
(SANDAG).
The value of travel forecasting using SANDAG’s
activity-based modeling comes from its capacity to
provide a full range of quantitative dimensions to
estimate travel-inducing activities and choices. The
model simulates daily activities and travel patterns in
the region, as affected by the transportation level of
service, and it simulates the effects of transportation
and land development patterns and policies on the
quality (time and cost) and quantity (traffic volume,
congestion, and VMT) of travel by different modes
(walk, bike, transit, and auto).
However, the VMT data that is provided by SANDAG
does not account for interregional trips. Put another
way, SANDAG’s data does not reflect the miles that are traveled beyond the county border or those trips
originating from outside the county. As such, the city
takes the SANDAG travel demand model data and
combines it with the regional transportation model
data that is collected by Caltrans. This combined data
is then used to create local VMT analysis maps that better forecast a full accounting of VMT, not limited
by regional boundaries, as recommended by the
Technical Advisory. The resulting maps from this
modeling show three color intensities:
• Green color represents areas in the city where
projects will likely have a less than significant
VMT impact and therefore no further VMT
analysis is required (i.e., areas in the city where
the model shows that development, for VMT
purposes, should be located);
• Medium blue color represents areas that are
likely to have a significant VMT impact, but one
that could potentially be mitigated with VMT
reducing measures to a level of less than
significant (i.e., areas in the city where the
model shows that development, for VMT
purposes, is not ideally situated, but the impacts
could be mitigated through measures such as
those identified in the city’s Transportation
Demand Management Plan); and,
IB-160_Vehicle Miles Traveled_September 2025 Page 5 of 8
• Darkest blue color represents areas that are
likely to have a significant VMT impact and are
unlikely to fully mitigate that impact (i.e., areas
where the model shows that development, for
VMT purposes, is not preferred and a full
Environmental Impact Report may be required to analyze the magnitude of the impacts.
Residential, office, and industrial projects generating
under 2,400 Average Daily Trips (ADT) can utilize
these VMT Maps. Projects that generate over 2,400
ADT, or retail projects that do not meet screening
criteria discussed earlier in this bulletin, must perform
project-specific modeling consistent with OPR
guidelines.
The 2,400 threshold comes from the document
entitled “Guidelines for Transportation Impact Studies
in the San Diego Region,” as prepared by a SB 743
subcommittee led by the Institute of Transportation
Engineers. Staff from SANDAG and Caltrans were on
this subcommittee along with transportation
engineers from the region.
Sometimes showing the math helps folks better
understand how the analysis works. This is one way of
calculating VMT impacts.
THEORETICAL PROJECT
A law firm is locating in Carlsbad and proposing to
construct a new two-story office complex on a vacant
lot located near the corner of Carlsbad Village and Pio
Pico Drive. The size of the office building is anticipated
to generate an ADT of 1,500 trips and the site is
designated in the VMT maps with a medium blue color.
Per city VMT maps, the regional mean is shown as 20.6
VMT/employee and the office project will have a
VMT/employee of 18.71, which is 90.8 % of the
regional average (18.7 divided by 20.6).
Per the city’s significance threshold, a significant
transportation impact occurs when an office project
exceeds a level of 15% below the regional average, or
another way of stating this is the project exceeds 85% of the regional average. 85% of the regional average is
17.5 VMT/employee. As such, in this theoretical
example, the percentage of project VMT that must be
reduced is 6.4% (1-(17.5/18.7)).
It is important to note that travel demand modeling is
very sensitive to input changes. As growth and
transportation system development occurs in the
region, which is inconsistent with the assumptions
used in the model, SANDAG will adjust the model to
keep the analysis current and reliable for CEQA
review. The city defaults to the most recent version of
SANDAG’s model, which is typically updated every
four years when SANDAG updates its regional plan.
Sometimes the model needs to be updated sooner to
account for changes in land use assumptions such the
city’s housing rezone program that was completed as
part of its 2021-2029 Housing Element.
Lastly, applicants are not restricted to use of these
maps as the city accepts other modeling strategies
that are consistent with the Technical Advisory (see
“Common VMT Questions” later in this bulletin for
additional information).
VMT Mitigation
Under CEQA, projects resulting in a significant impact
requires that mitigation measures be applied in an
effort to reduce VMT impacts to the extent feasible.
There are two ways to do this.
• Reduce the number of automobile trips
generated by the project; and/or,
• Reduce the distance people drive.
A project can accomplish this by incorporating
Transportation Demand Management (TDM)
strategies or actions into the development. Some
examples include rideshare programs, trip reduction
marketing, charging to use parking, employer paid
transit expenses, end-of-trip bicycle facilities, and
improvements to existing infrastructure such as bike
paths and sidewalks.
TDM strategies can be quantified using the
methodologies described in the ”Handbook for
Analyzing Greenhouse Gas Emission Reductions,
Assessing Climate Vulnerabilities, and Advancing
Health and Equity” (GHG Handbook). As mentioned
above, CEQA requires that cities use the most reliable
information available --- this document meets this
requirement and is currently used by virtually all state
jurisdictions when developing VMT mitigation.
Page 6 of 8 IB-160_Vehicle Miles Traveled_September 2025
The resource document provides a description of each
TDM measure with examples, notes on which
measures must be grouped with others to be
effective, a range of effectiveness (how much VMT
reduction will be achieved), and guidance on how the
measure should be implemented.
Some of the TDM measures can be combined with
others to increase the effectiveness of VMT
mitigation; however, the interaction between the
various strategies is complex and the effectiveness
levels are not directly additive --- simply adding
together the maximum VMT reduction values of
multiple TDM measures will not provide a true
representation of the total VMT expected to be
reduced. This is because some TDM measures, when
combined with others, may become redundant.
Per the GHG Handbook, maximum VMT reductions
are dependent upon the category of TDM measures
implemented, which are defined as subsectors.
Subsector maximums are intended to ensure that
emissions are not double counted when measures
within a given subsector are combined. For example,
the subsector maximum for “Trip Reduction
Programs” is 45% of a project’s commute VMT.
For a TDM program consisting of many measures, care
must be taken to verify that the calculated VMT
reductions are dampened (diminished) according to a
multiplicative formula to account for the above-
mentioned redundancies. This formula can be found
on page C-2 of the city’s guidelines but let’s use the
sample project above to show how a TDM program
made up of multiple measures is discounted.
THEORETICAL PROJECT, CONTINUED…
As shown previously, the office project requires a
6.4% reduction in VMT to have a transportation
impact that is less than significant under CEQA. As
such, the applicant proposes two TDM measures
from the GHG Handbook to mitigate this impact.
• Rideshare Program (3.2% VMT reduction)
• Commute Trip Marketing (4.0% VMT reduction)
To address anticipated redundancies when applying
multiple TDM measures, the following GHG
Handbook dampening equation must be applied.
1 - [(1-Pa) X (1-Pb) X (1-Pc)] = Total VMT Reduction
(where Px is percent reduction of a TDM measure)
After applying this dampening equation to the
proposed TDM measures for the theoretical office
project, the anticipated VMT reduction for the
project is adjusted to 7.1%.
1 - [(1 -3.2%) X (1-4.0%)] = 7.1%
Since 7.1% is more than the minimum 6.4%
reduction needed, the proposed TDM measures,
which will be added as conditions to the project
permit, will adequately reduce the project’s
transportation impacts to a level of less than
significant.
COMMON VMT QUESTIONS
VMT analysis is new and evolving, which has resulted
in a lot of confusion and questions in its
appropriateness and effectiveness. This info-bulletin is
intended to explain to the reader the value, aptness,
and usefulness of measuring and mitigating
transportation impacts through the reduction of VMT.
However, given its technical nature, there are some
common questions that warrant discussion.
IB-160_Vehicle Miles Traveled_September 2025 Page 7 of 8
Why are new projects only required to
implement minimum TDM measures?
This question comes up a lot during the review of new
development projects --- particularly in areas where traffic congestion is already an issue or existing
infrastructure (e.g., bus stop) is lacking or deficient.
CEQA Guidelines §15126.4(a) requires lead agencies
(city) to consider and require feasible mitigation
measures to avoid or substantially reduce a proposed
project's significant environmental impacts. The key
word here is the project’s impacts. The city cannot
legally require a project to make improvements to
resolve transportation deficiencies that existed prior
to the project being developed; the city can only
require mitigation that addresses the direct and
cumulative impacts generated by the proposed
development.
The due process clause of the Fifth Amendment of the
US Constitution further addresses this point. Pursuant
to the US Constitution, local governments can exact
property, or something of value from a property
owner (developer), without having to provide
compensation, provided two tests are met:
• “Nexus”
• “Rough Proportionality”
Nexus means the exaction (TDM mitigation) must
have a rational connection (nexus) to the burden the
government seeks to avoid (increased VMT). The
nexus requirement derives from the court case Nollan
v. California Coastal Commission, 483 U.S. 825, 107 S.
Ct. 3141 (1987).
Rough proportionality means that the amount of the
exaction (TDM mitigation) must roughly correspond to
the burden placed on the government/public
(increased VMT), resulting from the proposed
development. This test derives from court case Dolan
v. City of Tigard, 512 U.S. 374, 114 S. Ct. 2309 (‘94).
Using the theoretical project example, since the
rideshare and commute trip reduction marketing
programs address the VMT impacts of the office
project to a level of less than significant, the city
cannot require that the same project also improve a
nearby transit stop or add a turn lane to an existing
intersection to improve existing traffic flows as a mitigation requirement under CEQA. To do so would
violate both tests.
That said, there may be other city policies that require
multimodal improvements and transportation
demand management strategies. The city may impose
additional project requirements in order to satisfy
these mobility policies IF the city finds that the VMT
mitigation does not adequately address them. In other
words, VMT CEQA mitigation can also be used to
satisfy other city mobility policies.
Why are applicants allowed to use customized
VMT models?
While the SANDAG model is the city’s default model
to analyze project level VMT impacts, it is not without
its limitations. The SANDAG model makes certain
general assumptions on how land will be
develop/redeveloped. However, proposed
development projects, or the surrounding
development area, may be a particular size or contain
certain features that were not or could not be
accounted for in the SANDAG model.
Recognizing this, the Technical Advisory, and in turn
the city, allows applicants to develop customized
models using varying model strategies. Travel demand
models, sketch models, spreadsheet models, research,
and data can all be used to calculate and estimate
Page 8 of 8 IB-160_Vehicle Miles Traveled_September 2025
VMT. Models can also work together. For example, an
applicant can use travel demand models or survey
data to estimate existing trip lengths and input those
into sketch models to achieve more accurate results.
When using alternative models and tools, however,
the city requires consultants to use comparable data
and methods in order to set up an “apples-to-apples”
comparison between thresholds, VMT estimates, and
VMT mitigation estimates.
Why do some TDM measures work for some
projects, but don’t work for others?
There are some limits to overall VMT reduction
effectiveness depending on a project’s land use
context --- Developable area, proposed land use mix,
surrounding development patterns, and availability of
transit resources can vary significantly from project to
project. Similarly, so can the effectiveness of TDM
measures. For this reason, VMT mitigation measures
must be reviewed on a case-by-case basis to ensure
that they are site appropriate, justified, and can be
reasonably incorporated in the proposed project.
Why does the city use traffic analysis zones for
VMT analysis?
Daily activities
and travel
patterns in any
city is greatly
influenced by
existing land use
patterns and
transportation
networks. To
maximize the
effectiveness of a
predictive model,
it is important to assess VMT impacts in smaller, more
focused geographic areas.
SANDAG provides transportation model data in two
different ways: Census Tracts and Traffic Analysis
Zones (TAZ). Some people may be familiar with Census
Tracts (image right), which are small geographical
subdivisions of a county that help present different
statistical data points (i.e., average age, ethnicity,
household income, household size), with each tract
representing a population size between 1,200 and
8,000 people. A TAZ is a similar geographical area, but
typically much smaller than a census tract and most
commonly used in transportation models.
Use of either geographic area is perfectly acceptable
for VMT analysis. However, the city prefers to use TAZ
data because the TAZ offers a more refined area
around the project. The data tends to be a better
representation of the VMT in the area of the project
as opposed to the census tract where the VMT is
averaged across larger areas.
YOUR OPTIONS FOR SERVICE
To learn more, please contact one of our staff in Land
Development Engineering at 760-602-2750 or via
email at LandDev@CarlsbadCA.gov.
C] City of Carlsbad
-Less than 85%
85% to 100%
-100% or more (above average)
Attachment D
N
A
2035 Vehicle Miles Traveled (VMT) per Resident by Traffic Analysis Zone (TAZ)
Comparison to ABM2+ City-wide Average -23.6 Miles per Resident
\
c:::J City of Carlsbad
Less than 85%
85% to 100%
-100% or more (above average)
Bu
' \
N
A
Figure 2
2035 Vehicle Miles Traveled (VMT) per Employee by Traffic Analysis Zone (TAZ)
Comparison to ABM2+ Regional Average -20.1 Miles per Employee