Rethinking How We Build So Californians Can Drive Less
Caltrans is committed to providing Californians with access to destinations while reducing the amount of motor vehicle traffic required to achieve that access. This is a departure from past practice, when adding to the supply of roadways was the default option. But over many years of observation and analysis, we have learned that adding supply has a paradoxical outcome. It generates more driving, which is both costly to personal budgets and the environment, and which often re-congests the very roadways we built or expanded.
Senate Bill (SB) 743 Implementation
Addressing induced travel was one of the motivations behind SB 743 (2013), which amended the state’s long-standing, premier environmental law, the California Environmental Quality Act. Among other things, legislators and many constituents were concerned that old rules under the “level-of-service” rubric (LOS) were too focused on keeping traffic speeds up and therefore making it hard to build infill housing and other land uses in denser areas. State guidance and local regulations adopted in the wake of SB 743 have removed those burdens in many places, allowing needed development to proceed in areas that tend to generate little new traffic.
In 2020 Caltrans adopted its guidance under SB 743. The department’s Transportation Analysis Framework and Transportation Analysis for CEQA provide guidance for assessing induced travel impacts from prospective projects on the State Highway System. Another document, the Transportation Impact Study Guide, provides guidance for Caltrans’ comments to land-use authorities.
This guidance, which reflects a major change in the department’s approach, came after extensive research and consultation with experts and stakeholders. The guidance does not answer every question about induced traffic, however, so efforts to amend or extend it are continuing. For example, in June 2021, Caltrans and the Governor’s Office of Planning and Research kicked off a multi-year working group composed of 40 stakeholders to help us address unanswered questions and generally improve the departments’ processes around induced travel. We also have staff around the state working with regional and local entities on the same issues. We welcome any inquires at firstname.lastname@example.org
The methods by which projects may spur more driving, called “induced traffic” or “induced demand,” are clearly laid out in the department’s “Transportation Analysis Framework” (TAF). Induced traffic tends to result from projects that increase travel speeds, such as roadway capacity additions. Such projects allow drivers to take new or longer trips, and to move from transit or other non-auto modes to driving. In addition, greater speeds spur land uses to spread out, increasing travel distances. After a while, that extra traffic again causes congestion, but the spread-out land uses remain, so travelers must spend more time and money reaching desired destinations, with greater emissions. On the other hand, non-automotive projects – those around transit, walking, and biking – tend to reduce motor vehicle travel.
A panel of experts informed the TAF’s induced travel methodology and is summarized in the Expert Panel Report (PDF).
Transportation Impact Study Guide
The TISG details how the Caltrans Local Development-Intergovernmental Review (LD-IGR) program reviews a land use project's VMT
Updated Interim LD-IGR Safety Review Guidance
The document updates Caltrans new, simplified safety review for Caltrans review land use project.
Transportation Analysis Framework
The TAF details methodology for calculating induced demand for capacity increasing transportation projects on the State Highway System.
Transportation Analysis under CEQA
The TAC provides guidance for making CEQA significance determinations for transportation projects along the State Highway System.
The legal CEQA jargon of SB 743 can be difficult to communicate simply. Our two Fact Sheets below can help ease that process.
Reducing VMT does not mean removing access to destinations. Watch our short video series, "SB 743: Rethinking How We Build So Californians Can Drive Less," to find out more about how we are thinking about this new paradigm.
The Need for SB 743 (4:03)
Benefits of SB 743 (3:49)
References & Tools
- Technical Advisory: How to evaluate transportation impacts [OPR]
- CEQA Guidelines: Implementing SB 743 (pp. 11-12) [CA Natural Resources Agcy]
- CARB 2017 Scoping Plan: Connecting State Climate Goals and VMT
- Induced Travel Calculator: Allows users to estimate annual VMT as a result of highway expansion
- OPR SB 743 Page: Additional, related resources for implementation
- Transportation Under CEQA Analysis eLearning
Evaluation of Sketch-Level Vehicle Miles Traveled (VMT) Quantification Tools: National Center for Sustainable Transportation "researchers compare and evaluate VMT estimation tools across a sample of land use projects. They compare the results from different tools for each project, consider the applicability of methods in particular contexts and for different types of projects, and assess data needs, relative ease of use, and other practical considerations." The research is not done within a CEQA context, but it is interesting to review the use of the VMT estimation tools.
SB 743 Case Studies: The Urban Sustainability Accelerator at Portland State University created five case studies on how to apply the vehicle miles traveled metric to a highway project and three land use projects.
- The San Diego Section of the Institute of Transportation Engineers (ITE) has prepared updated regional Transportation Impact Study Guidelines to incorporate SB 743. The May 2019 document titled "Guidelines for Transportation Impact Studies in the San Diego Region" is available on ITE San Diego's TCM Task Force page.