research report

How the Built Environment Affects Car Ownership and Travel: Evidence from San Francisco Housing Lotteries

Abstract

Credibly identifying how the built environment shapes behavior is empirically challenging because people select residential locations based on differing constraints and preferences for site amenities. The study overcomes these research barriers by leveraging San Francisco’s affordable housing lotteries, which randomly allow specific households to move to specific residences. Using administrative data, the research team demonstrates that lottery-winning households’ baseline preferences are uncorrelated with their allotted residential features such as public transportation accessibility, parking availability, and bicycle infrastructure—meaning that neighborhood attributes and a building’s parking supply are effectively assigned at random. Surveying the households, the team finds that these attributes significantly affect transportation mode choices. Most notably, the research paper shows that essentially random variation in on-site parking availability greatly changes households’ car ownership decisions and driving frequency, with substitution away from public transit. In contrast, the research team finds that parking availability does not affect employment or job mobility. Overall, the evidence from the study robustly supports that local features of the built environment are important determinants of transportation behavior.

dissertation, thesis, or capstone

Gaining Wait? Analyzing the Congestion Impacts of Road Diets in Los Angeles

published journal article

Induced Vehicle Travel in the Environmental Review Process

Abstract

If we expand roadway capacity, more drivers will come, or so economic theory suggests and a substantial body of empirical research now shows. Despite strong evidence, the “induced travel” effect is often ignored, underestimated, or misestimated in the planning process, particularly in the assessment of the environmental impacts of roadway capacity expansions. Underestimating induced travel will generally lead to an overestimation of the traffic congestion relief benefits a highway expansion project might generate, along with an underestimation of its environmental impacts. A major reason that induced travel tends to be underplayed in environmental analyses is that travel demand models do not typically include all of the feedback loops necessary to accurately predict the induced travel effect. We developed an online tool, based on elasticities reported in the literature, to facilitate the estimation of the induced vehicle travel impacts of roadway capacity expansion projects in California, with potential future expansion to other geographies. We describe the tool, apply it to five case study highway capacity expansion projects, and then compare the results with the induced travel estimates reported in the environmental impact analyses for those projects. Our results suggest that environmental analyses frequently fail to fully capture the induced vehicle travel effects of highway capacity expansion projects.

policy brief

Defining Sensitive Communities Under SB 50

Abstract

In this brief, we analyze the coverage of the definition of “sensitive communities” that was included in the March 2019 revisions to theSB 50 bill language – we call this the “SB 50 Sensitive Communities” definition. We also present analysis of two alternative metrics –California SB 535’s definition of “Disadvantaged Communities” and the U.S. Department of Housing and Urban Development’s “Racially/Ethnically Concentrated Areas of Poverty” (R/ECAPs) –as comparison points. We present these comparisons as a way to discuss how different definitions influence which places would bedesignated as sensitive communities, rather than to recommend one definition over another. Developing an empirical metric to identify sensitive communities is complicated, as there is no one factor that perfectly measures vulnerability to displacement and marginalization, especially when one considers the diversity of places in California. This brief is thus designed to provide stakeholders with information about the currently proposed definition, as well as to highlight questions related to the provision’s implementation. The brief is accompanied by an interactive map,which allows stakeholders to see how the different definitions play out in their own communities.

policy brief

Electric Bike-share in the Sacramento Region is Replacing Car Trips and Supporting More Favorable Attitudes Towards Bicycling

Abstract

Bike-share services have rapidly expanded in cities worldwide and attracted substantial ridership, especially as electric and dockless bike- and scooter-share services have entered the market. These services have the potential to offer a healthier and more environmentally sustainable mobility option if used as an alternative to car travel and a connection to transit. However, little is known about the influence of bike-share systems on individual travel behavior; particularly if bike-share trips are replacing vehicle trips and increasing transit use. To address this knowledge gap, researchers at the University of California, Davis surveyed Sacramento-area residents before and after the 2018 implementation of a JUMP/Uberoperated dockless electric bike-share program to examine how the micromobility service influenced general travel behavior and attitudes. Surveys were sent to residents in downtown Sacramento, West Sacramento, and Davis within the bike-share service area and to a control group in Sacramento outside the service area. Key findings from the research are summarized in this brief.

policy brief

Clean Air in Cities: Impacts of the Layout of Buildings in Urban Areas on Pedestrian Exposure to Traffic-Related Pollutants

policy brief

Upzoning Under SB 50: The Influence of Local Conditions on the Potential for New Supply

Abstract

In this brief, the researchers explore what might happen were SB 50 to pass by taking a detailed look at local market conditions in four case study neighborhoods. Local context shapes financial and physical feasibility. When SB 827, the predecessor to SB 50, was under consideration, estimates of its impact on new housing supply were optimistic. Yet, most of these estimates focused on aggregate development potential and did not consider the on-the-ground reality of other zoning provisions that may influence development, what types of projects might pencil out, or what the existing stock looks like.

policy brief

Drivers of Partially Automated Vehicles are Making More Trips and Traveling Longer Distances

Abstract

Consumers are purchasing and using partially automated vehicles, yet little research has been conducted to understand how and if these vehicles are changing travel behavior. Fully automated, or driverless, vehicles are receiving much more research and policy attention but are still many years from market introduction. Research on fully automated vehicles has shown that, without proper policies in place, these vehicles could increase vehicle miles travelled (VMT). Tesla vehicle models with the ‘Autopilot’ feature are some of the most common partially automated vehicles on the road today. A partially automated vehicle provides advanced driver assistance by controlling steering, acceleration/ deceleration, and braking; however, the human driver is still considered to be in control of the vehicle and is expected to be attentive. A previous UC Davis study found that Tesla vehicle owners with the Autopilot feature drove more than those without Autopilot, but the study did not determine whether higher VMT was caused by Autopilot. To better understand whether Autopilot influences how much individuals drive, the UC Davis research team interviewed 36 Tesla Autopilot users to evaluate whether they experienced changes to their travel, and the reasons for any reported changes. Key findings from the interviews are presented in this brief.

research report

Travel Behavior Changes Among Users of Partially Automated Vehicles

Abstract

Partially automated battery electric vehicles (BEVs) are being sold to and used by consumers. Estimates indicate that as of the end of 2019, there were over 700,000 Partially Automated Tesla Vehicles—the subject of this study—on the roads globally. Despite this, little research has been done to understand how they may be changing travel behavior. In this study, qualitative interviews with 36 users of Tesla battery electric vehicles with Autopilot were conducted. The goal of this was to understand how Autopilot is used, user experiences of the system, and whether the system has any impact on drivers’ travel behavior. The focus of the last of these aims was to determine whether Autopilot could cause or was causing an increase in vehicle miles traveled (VMT) among the study participants. Results from the interviews showed that partial automation leads to consumers traveling by car more and being more willing to drive in congested traffic. These changes are due to increased comfort, reduced stress, and increased relaxation due to the partial automation system, and because of the lower running costs of a BEV. The results also point to a need for further research of partially automated vehicles that are already on the market, as 11 of 17 reasons for increased vehicle miles traveled that have been identified in modeling studies of fully automated vehicles (not yet commercially available) applied to users of Autopilot.