Exploring the Induced Travel Effects from Minor Arterials, Auxiliary Lanes, and Interchanges

A robust body of empirical research demonstrates that as roadway supply increases, vehicle miles traveled (VMT) generally does, too. The evidence is particularly strong with respect to major roadways, like interstate highways (class 1), other freeways and expressways (class 2), and principal arterials (class 3). However, previous literature reviews have found limited empirical evidence as to the relative magnitude of the induced travel effect of expanding minor arterials, collector streets, and local roads. Previous reviews have similarly not reported empirical research on the induced travel effects of other types of roadway facilities, such as auxiliary lanes, ramps, or other types of interchanges. In this project, the authorsconducted a systematic literature review on the induced travel effects of minor arterials, auxiliary lanes, and interchanges (including simple on/off ramps). The authors found that the empirical literature remains limited with respect to auxiliary lanes and interchanges. They found eight studies that include minor arterials in their empirical estimates of induced travel, which collectively indicate that the induced travel elasticity for class 4 minor arterials could be similar to that of class 1-3 facilities. However, none of the studies isolated the induced travel effect from minor arterials specifically. Going forward, the report suggests avenues for future research to help close these research gaps. For example, the authors recommend using case studies of individual roadway expansions to better understand the induced travel effects specific to ramps, interchanges, minor arterials, and auxiliary lanes within specific contexts, especially where larger studies (across multiple facilities, geographies, etc.) have not yet been done. View the NCST Project Webpag

Exploring the Equity Effects of VMT Mitigation Measures

In 2018, pursuant to Senate Bill (SB) 743 (2013), the Governor’s Office of Planning and Research (OPR) and the California Natural Resources Agency promulgated regulations and technical guidance that eliminated automobile level of service (LOS) as a transportation impact metric for land development projects under the California Environmental Quality Act (CEQA), and replaced it with Vehicle Miles Traveled (VMT). The authors investigated the equity effects of VMT mitigation measures and developed a framework for evaluating those effects at the project level. The authors then applied the framework to two highway expansion case studies in California. They found that most VMT mitigation would be implemented at least partially within the project impact areas, as well as some disadvantaged communities, but would generally benefit communities outside of the project area, too. Most of the proposed mitigation measures would not displace existing residences or businesses or pose a significant risk of gentrification. Many of the measures showed substantial potential to improve accessibility to jobs, though less potential to improve accessibility to grocery stores. Community engagement and empowerment was harder to gauge. Overall, the five-part framework can provide a first-cut assessment of the equity effects of VMT mitigation measures during the environmental review phase of VMT-generating projects, like roadway expansions.View the NCST Project Webpag

The Induced Travel Calculator and Its Applications

The National Center for Sustainable Transportation’s Induced Travel Calculator (Calculator) has generated substantial interest in the professional community as a method for estimating the additional vehicle miles traveled (VMT) induced by expanding the capacity of major roadways. The Institute of Transportation Studies at the University of California, Davis (ITS-Davis) initiated a technical assistance project to support Caltrans and others in applying the Calculator. This report: (1) provides an overview of the Calculator and the induced vehicle travel effect, (2) summarizes the results from an earlier study comparing the Calculator’s estimates with other induced travel analyses, (3) describes the technical assistance efforts and outcomes, and (4) discusses plans for future improvements to the Calculator. During the project, ITS-Davis advised Caltrans as it developed its Transportation Analysis Framework to guide transportation impact analysis for projects on the State Highway System. Caltrans published the final document in September 2020, in which it recommends that the Calculator be used where possible to estimate induced VMT. ITS-Davis also advised on efforts to apply the Calculator’s elasticity-based method to estimate induced VMT from out-of-state highway capacity expansion projects, including projects in Portland, Oregon, Washington, D.C., Kenya, and China. In a follow-up project, ITS-Davis will work with Caltrans to improve the Calculator documentation to answer questions raised by Caltrans and others, explore possible technical improvements to the Calculator, and explore opportunities for assessing the validity of the Calculator’s induced VMT estimates

The Induced Travel Calculator and Its Applications

The National Center for Sustainable Transportation’s Induced Travel Calculator (Calculator) has generated substantial interest in the professional community as a method for estimating the additional vehicle miles traveled (VMT) induced by expanding the capacity of major roadways. The Institute of Transportation Studies at the University of California, Davis (ITS-Davis) initiated a technical assistance project to support Caltrans and others in applying the Calculator. This report: (1) provides an overview of the Calculator and the induced vehicle travel effect, (2) summarizes the results from an earlier study comparing the Calculator’s estimates with other induced travel analyses, (3) describes the technical assistance efforts and outcomes, and (4) discusses plans for future improvements to the Calculator. During the project, ITS-Davis advised Caltrans as it developed its Transportation Analysis Framework to guide transportation impact analysis for projects on the State Highway System. Caltrans published the final document in September 2020, in which it recommends that the Calculator be used where possible to estimate induced VMT. ITS-Davis also advised on efforts to apply the Calculator’s elasticity-based method to estimate induced VMT from out-of-state highway capacity expansion projects, including projects in Portland, Oregon, Washington, D.C., Kenya, and China. In a follow-up project, ITS-Davis will work with Caltrans to improve the Calculator documentation to answer questions raised by Caltrans and others, explore possible technical improvements to the Calculator, and explore opportunities for assessing the validity of the Calculator’s induced VMT estimates

SB 743 Implementation by Local Governments for Land Use Projects

In 2018, pursuant to Senate Bill (SB) 743 (2013), the Governor’s Office of Planning and Research (OPR) and the California NaturalResources Agency promulgated regulations and technical guidance that eliminated automobile level of service (LOS) as a transportation impact metric for land development projects under the California Environmental Quality Act (CEQA), and replaced it with Vehicle Miles Traveled (VMT). The authors investigated how local governments have been implementing the LOS-to-VMT shift for land development projects, and how that differs from past practice. They also explored whether local governments monitor the actual VMT impacts from completed land use developments and what methods are available to do so. Their findings indicate that all responding jurisdictions acknowledged the mandatory LOS-to-VMT shift, but were in varying stages ofimplementing the shift. For those jurisdictions that had adopted VMT impact significance thresholds, most adhered closely to OPR’s recommendations. They also mostly tried to use apples-to-apples methods of calculating baseline VMT levels (for setting thresholds) and estimating project-level VMT, often relying on travel demand model outputs for both. However, most jurisdictions gave short shrift to VMT monitoring. Another important aspect of SB 743 implementation is how LOS will continue to be used outside of CEQA. The authors found that jurisdictions uniformly continue to employ LOS outside of CEQA. However, those LOS analyses are not necessarily as comprehensive and expensive as they would have been for CEQA purposes. The authors found a consensus amongst their interviewees that swapping LOS for VMT could streamline development in urban areas.View the NCST Project Webpag