A New Measure of Transportation Impact

California has made a sweeping break with its own past policy and national practice; traffic congestion is no longer considered a potentially significant environmental impact under the California Environmental Quality Act (CEQA).  

Instead, the amount of driving – as measured by “vehicle miles traveled” – is the new lens for assessing transportation impacts on the environment for projects subject to CEQA review. And reducing the amount of driving is the way in which these impacts are reduced (or “mitigated” in the terminology of CEQA.)  

Initiating this change was California Senate Bill 743, passed in 2013 and implemented in 2018 through the adoption of new CEQA regulations, or “guidelines.”  The chief sponsor of SB 743 was then Senate President Darrell Steinberg, now mayor of Sacramento. 

Goal of SB 743

SB 743, which addresses a range of topics, aims to better promote statewide policies that (a) combat climate change by reducing greenhouse gas emissions and particulates; (b) encourage infill development and a diversity of uses instead of sprawl; and (c) promote multi-modal transportation networks, providing clean, efficient access to destinations and improving public health through active transportation.

As a result of SB 743, traditional measures for mitigating congestion (e.g., widening roads, adding turn lanes, and making similar investments in the transportation network) will be replaced with measures that mitigate additional driving, such as increasing transit options, facilitating biking and walking, changing development patterns and charging for parking.

Purpose of this Project

The SB 743 Implementation Assistance Project: From Driving More to Driving Less – was undertaken to help government agencies, businesses, and citizen groups implement this substantial change, particularly at a technical level. Nearly one hundred people participated in the project, which resulted in a set of case studies, workshops, presentations, resources, and an online course that are posted on this website.

Hundreds of people attended or watched the workshops and the professional education program, which is available for credit, and is based on the results of the work. 

The case studies illustrate a variety of methodologies for quantifying vehicle miles traveled (VMT) in order to assess a project’s transportation impacts and find ways to mitigate additional VMT in compliance with CEQA. They also compare VMT impact assessment to the former level of service (LOS) congestion metric.  The workshops focused on VMT mitigation measures at a variety of geographic scales, and explored the concept of a VMT mitigation exchange system. 

The case studies and other materials produced by the project will be helpful to the staff leading environment impact reviews and their project partners in carrying out their responsibilities under CEQA. 

DISCLAIMER: These case studies and other materials are not offered as opinions of the proper interpretation and application of SB 743, or more generally of CEQA.  They cannot be relied upon as authoritative or binding interpretations of either.