VMT reduction planning for state transportation projects

While reduction of vehicle miles travelled (VMT) has sometimes been considered in state planning to reduce greenhouse gas emissions, it is increasingly being used as part of transportation planning and project approval at the state level. In this article, we review the growing practice through examples from California, Colorado, Minnesota, and Washington—identifying emerging environmental impact and equity considerations.

California VMT reduction planning for transportation projects

In September 2020, the California Department of Transportation (Caltrans) issued the first editions of the Transportation Analysis under CEQA (TAC) and Transportation Analysis Framework (TAF), which is a companion document to the TAC. These guidance documents implement changes from California Senate Bill 743 (SB 743) that required a shift away from using metrics that measure traffic delay or congestion to metrics that promote reduction of greenhouse gas emissions, development of multimodal transportation networks and diversity of land use, to metrics such as vehicle miles travelled, for evaluation of most projects under the California Environmental Quality Act (CEQA). SB 743 took effect on July 1, 2020, but transportation planners are still grappling with the consequences of this shift nearly four years later.

The TAC guidance provides direction on CEQA analysis for transportation projects on Caltrans’ State Highway System. The TAF guidance provides direction on the States’ preferred approach and analytical methods to estimate the VMT attributable to transportation projects in various project settings.

The 2018 CEQA Guidelines Update, Section 15064.3 (b)(2), grants an exception to allow lead agencies the discretion to choose the appropriate measure in evaluating the significance of transportation impact(s) under CEQA for capacity-increasing roadway projects. What this means is that VMT is not a mandatory metric for CEQA analysis of capacity-increasing roadway projects and that traffic delay metrics could be used at the discretion of the lead agency if they are consistent with CEQA and other applicable requirements. However, as described in the TAC, Caltrans has chosen to use VMT as the primary transportation metric for CEQA analysis of projects on the State Highway System. This is a significant paradigm shift from a focus on addressing traffic delay and congestion in CEQA analysis to a focus on reducing VMT. 

The TAC identifies a wide range of non-capacity increasing projects not likely to result in measurable increases in VMT. In addition, the TAC notes that there are also some projects where the addition of pavement or lanes, the extension of lanes, or the conversion of lanes may be involved but are not likely to measurably increase VMT, including:

• Road shoulder improvements for safety.
• Auxiliary lanes less than one mile in length to improve safety.
• General-purpose lane conversions to managed or transit lanes.
• Transit-only lane additions.
• Passing lanes, truck climbing lanes, or truck brake-check lanes in rural areas that do not increase overall corridor capacity.

For these projects, the TAC and TAF note that a qualitative assessment will usually be adequate under CEQA, and mitigation may not be warranted. However, it should be noted that the TAC states, “When concluding that a particular project may be screened out from further analysis, the practitioner should review and fully document the rationale supporting the conclusion that the particular project would not likely lead to a measurable and substantial increase in VMT.”

The TAC states that capacity-increasing projects are likely to measurably and substantially increase VMT, including the addition of through lanes on existing or new highways—such as general-purpose lanes, high occupancy vehicle (HOV) lanes, peak period lanes, auxiliary lanes, or lanes through grade-separate interchanges—and other projects adding capacity to the State Highway System. The TAF describes the mechanisms by which induced travel can occur due to roadway capacity-increasing projects:

• Route changes (which may increase or decrease overall VMT).
• Mode shift in favor of automobile use (increases overall VMT).
• Longer trips (increases overall VMT).
• More trips (increases overall VMT).
• More dispersed development (increases overall VMT).

For capacity-increasing projects, the TAC and TAF describe that a quantitative analysis would normally be warranted, and in practice this has been required for capacity-increasing projects throughout the State. The recommended baseline is future (generally defined as 20 years from a project’s projected open to traffic year) without project conditions. While CEQA normally considers existing conditions to be the appropriate baseline, CEQA allows for the use of future without project conditions when the project’s effects are best identified compared to such future conditions.

The TAF lists two quantitative methods for estimating project effects on VMT: an approach applying travel demand elasticities from empirical studies that quantify the induced travel effect, and a travel-demand model-based approach.

The TAF states that the University of California, Davis National Center for Sustainable Transportation Induced Travel Calculator can be used for the empirical approach and is recommended for use in many urban counties for capacity-increasing projects on freeways and state routes. The TAF recommends use of a travel demand model approach for capacity-increasing projects on freeways in certain urban counties, in rural counties with congestion near the project site, and for other potentially VMT inducing projects on a state route. The TAF provides guidance and limitations on using these two approaches. 

If the traffic impacts related to VMT cannot be mitigated to a level that is considered less than significant under CEQA, a statement of overriding conditions (SOC) may, and likely will be, needed for approval of the project. However, even if a SOC is adopted, CEQA requires that any identified feasible mitigation be implemented. For rural (non-metropolitan planning organizations [MPOs]) areas, the TAC states that significance should be addressed on a case-by-case basis, considering context and environmental setting.

Mitigation, where warranted, may include on-site or off-site strategies. The TAC describes that it may become increasingly difficult to achieve feasible and proportional project-level VMT mitigation as a project proceeds from initial scoping to final design, and in practice this has been found to be accurate by numerous agencies that have attempted to identify sufficient measures to reduce VMT to a level considered less than significant under CEQA. That's why it's important to thoroughly consider upfront a range of project alternatives that can potentially minimize, or avoid, the additional VMT from capacity-increasing projects.

On-site mitigation on the State Highway System is more within Caltrans’ direct authority than off-site mitigation, as off-site mitigation is generally under the authority of agencies with influence over land use and transportation systems outside of Caltrans’ direct control. While tolling of existing general-purpose lanes can also be an on-site mitigation strategy, it would require coordination with appropriate transportation planning agencies and may require approval of other state and federal agencies as well. The TAC identifies a range of other potential on-site mitigation measures, including:

• Incorporation of complete streets elements.
• Incorporation of alternate modes of transportation (including bicycle and pedestrian facilities and connections to transit).
• Park-and-ride lots.
• Social media marketing, public education, and incentives to promote trip reduction, use of transit, and carpooling.
• Intelligent transportation systems.
• Traffic management strategies to make bus operations more efficient and to develop a more interconnected transportation system.

When further on-site design features are not feasible or effective, the Caltrans Transportation Impact Study Guide (TISG) and TAC support off-site VMT mitigation approaches. As noted above, many of these are outside Caltrans’ direct authority and will require the cooperation of many other agencies, potentially including federal, state, regional, and local entities. These approaches include, but are not limited to:

• Land use planning.
• Cordon (or area) pricing.
• Parking management and pricing.
• Employer-based transportation demand management.
• VMT mitigation banks.
• VMT mitigation exchanges.
• VMT impact fee programs.

The first four approaches above are usually within the jurisdiction of local land use authorities and private development. VMT banking, exchange, or fee programs can be used to collect funding from projects with significant VMT impacts under CEQA and the funds used to support VMT reducing projects such as transit, bicycle, and pedestrian projects, or other strategies.

VMT banking, exchange, or fee approaches are in the early stages of development. The City of Los Angeles has completed a nexus study on setting transportation impact fees based, in part, on VMT. Various other agencies, including the San Bernardino County Transportation Authority (SBCTA), the Contra Costa Transportation Authority (CCTA), Los Angeles County Transportation Authority (LA Metro), the San Mateo City/County Association of Governments (C/CAG), and Santa Cruz County have explored or are exploring VMT banking, exchange, or fee approaches. In addition, the City of Riverside is looking at a VMT mitigation fee program.

The TISG and TAC also mention several useful studies of off-site banking, exchange, and fee program approaches completed by:

• The University of California Berkeley School of Law Center for Law, Energy, and the Environment.
• The State Smart Transportation Initiative.

One thing to note: Caltrans’ use of VMT for their capacity-increasing roadway projects does not preclude other lead agencies from using traffic metrics other than VMT for determining CEQA significance for their own local capacity-increasing roadway projects. Caltrans’ use of VMT only applies to projects where they are the CEQA lead agency. It is up to each CEQA lead agency to determine what metric they use for capacity-increasing roadway projects.

Other states picking up the VMT challenge

Beyond California, VMT is gaining ground as a measure of transportation impacts in other states. Colorado, Minnesota, and Washington are examples of states that are incorporating VMT reduction into their climate action and transportation planning.

Colorado

In Colorado, in 2019, the general assembly passed an aggressive greenhouse gas (GHG) reduction bill (HB 19-1261) to reduce GHG emissions by 50% in 2030 and 90% by 2050 (compared to 2005 levels). In 2021, the Colorado Transportation Commission established the GHG Transportation Planning Standard that requires the Colorado Department of Transportation (CDOT) and the state’s five MPOs to create transportation plans resulting in reduced GHG emissions including reductions beyond vehicle electrification.

In 2022, Colorado transportation planning agencies updated their plans and project lists to meet the new GHG reduction targets. The new plans spend less money on highway expansions and redirect funding toward transit, biking, and walking infrastructure. By supporting modal alternatives and more transportation-efficient land use patterns, the updated plans are expected to reduce total driving, or VMT, by up to 9% in 2030 (compared to baseline 2030 VMT).

Minnesota

In Minnesota, the 2022 Statewide Multimodal Plan developed by the Minnesota Department of Transportation (MnDOT) includes a goal to work with transportation partners to identify and advance statewide strategies for reducing per capita VMT by 20% by 2050 (compared to 2019 levels).

In 2023, the Minnesota legislature went even further with the 2023 transportation omnibus bill (Chapter 68- MN Laws) that requires MnDOT to assess proposed highway expansion projects for consistency with the established VMT and GHG reduction goals. If a proposed project does not conform with the VMT or GHG goals, the project must either be altered so that it does conform, or the impacts must be offset by linking the project to off-site impact mitigation actions.

Washington State

In 2021, the Washington State Legislature directed various state agencies including the Washington State Department of Transportation (WSDOT) to:

• Develop a process for establishing reduction targets for local VMT.
• Develop guidelines to help cities and counties integrate climate mitigation and resiliency goals into local comprehensive plans.
• Recommend a suite of options for local jurisdictions to achieve the targets.
• Identify funding requirements for state and local jurisdictions to achieve the targets.

Pursuant to these requirements, WSDOT issued a final report in June 2023 that include recommendations for WSDOT, Regional Transportation Planning Organizations (RTPOs) concerning VMT goals, monitoring, modeling, equity, implementation and recommendations to the legislature concerning foundational VMT rules, land use, parking reform, transportation options, transportation demand management, transportation system management.

National Environmental Policy Act (NEPA) and VMT

With the issuance of the Council on Environmental Quality (CEQ)’s NEPA Guidance on Consideration of Greenhouse Gas Emissions and Climate Change in 2023, NEPA lead agencies are encouraged to quantify the direct and indirect GHG emissions of proposed actions and their alternatives and to consider methods of potentially reducing these emissions.

The CEQ guidance does not contain any specific reference to transportation projects or VMT, but since VMT increases caused by fossil fuel vehicles result in an increase in GHG emissions, these emissions should be accounted for in NEPA analyses. Where appropriate, mitigation measures should be identified and considered to reduce GHG emissions, which may include measures to reduce VMT. NEPA requires the consideration of mitigation, although to date it has been generally interpreted by lead agencies to not mandate the imposition of mitigation (unlike CEQA).

Equity considerations and VMT effects

There are equity concerns related to VMT. In California, state law (SB 743) emphasized GHG reductions, land use diversity, and multimodal transportation networks in supporting VMT as a transportation metric. Beyond these elements, increasing VMT may result in localized secondary impacts such as increased criteria air pollutant emissions, noise, safety risks, and adverse changes in neighborhood aesthetics. Based on historical patterns of development and locations of major roadways, the adverse secondary effects of VMT often fall disproportionately on disadvantaged communities (see for example UCS 2019, Caltrans 2023, and Casey et al 2017, among others).

Consequently, equity considerations may be appropriate depending on the location of VMT increases and the location of VMT reductions. VMT increases in a disadvantaged community if not offset by VMT mitigation in that community can exacerbate historic inequities. However, common VMT reduction measures—such as investments in transit, pedestrian and bicycle facilities, or affordable housing—can be designed to benefit disadvantaged communities while also reducing VMT.

When areas of low employment also have high costs of housing this can result in lower-income households having to make long vehicle-dependent commutes from more affordable outlying areas. VMT reduction strategies (such as improved transit and first-mile/last-mile solutions) need to take into account how to provide mobility solutions for highly vehicle dependent lower-income households in this situation.

Agencies developing VMT mitigation programs can establish policy preferences to direct VMT mitigation to benefit equity should they choose to do so.

Partnering with clients on VMT analysis and identifying mitigation options

ICF actively supports clients in developing tools to analyze VMT and develop VMT mitigation, giving us hands-on insight into the challenges and solutions involved. Our team is supporting MnDOT with the development of their project impact assessment program, and we supported Caltrans in the development of a 2019 Literature Review and Assessment of VMT and GHG Strategies, which is included as an appendix to the TAC.

Another example of our work in this field is the Mobility Management Toolbox, developed with the San Diego Association of Governments. This toolbox includes: 

• Mobility management strategies.
• A VMT reduction calculator tool.
• Implementation guidance.
• Training videos.

ICF, working for the California Air Pollution Control Officer’s Association (CAPCOA) and the Sacramento Metropolitan Air Quality District (SMAQMD), developed the 2021 Handbook for Analyzing Greenhouse Gas Emission Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity (commonly referred to as the “GHG Handbook”) that includes methodologies for evaluating VMT reduction for more than 25 types of transportation measures.

We also developed a comprehensive update and expansion of CalEEMOD, which is a tool used to estimate criteria air pollutant and GHG emissions and mitigation—including those associated with VMT—as well as assess climate change vulnerability and identify adaptation measures to help support equity when planning land use development.

We assisted Caltrans’ Division of Transportation Planning to prepare a comprehensive update to the Local Development Review (LDR) training program to strengthen its focus on transportation infrastructure supporting smart growth and efficient development and in compliance with SB 743 requirements.

In partnership with other experts such as Fehr & Peers, ICF has also been supporting California transportation agencies explore CEQA mitigation strategies such as VMT mitigation banks, exchanges, and fees. If successful, these strategies would provide a potential pathway for mitigating VMT impacts for transportation projects. The uncertainty regarding how to mitigate for impacts related to VMT is one of the biggest challenges facing agencies in moving critical transportation projects forward, and the establishment of a bank, exchange, or fee program would address this uncertainty so that agencies can better plan for needed infrastructure improvements and be more certain of project mitigation requirements and costs.

Wherever transportation analysis and planning, NEPA, CEQA, VMT mitigation, and climate action planning trends go, we will closely monitor developments and continue providing insights. If one thing is certain, it’s change—keeping a finger on the pulse of transportation and climate action planning is as important as ever.