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Open Access Publications from the University of California
Cover page of Partially Automated Vehicles Are Increasing Vehicle Miles Traveled

Partially Automated Vehicles Are Increasing Vehicle Miles Traveled


Research is beginning to show that vehicle automation will encourage more driving because it substantially reduces driver workload, making driving more relaxing and less stressful. This will have environmental sustainability implications, given that vehicle electrification alone will not be sufficient to meet state and federal greenhouse gas reduction targets without reductions in vehicle miles traveled (VMT). Research on the effects of vehicle automation has been somewhat speculative because fully automated vehicles are not yet commercially available. But many automakers are already incorporating automated features such as adaptive cruise control and lane keeping assist into their vehicles. These features assist in driving tasks and reduce the “cost” of driving in much the same way fully automated vehicles promise to do. Researchers at UC Davis surveyed owners of partially automated electric vehicles in California to understand the impact of partial automation on VMT. The survey asked respondents about their use of partial automation systems including BMW Driving Assistant, Ford Co-pilot360, Honda Sensing, Nissan ProPilot Assist, Tesla Autopilot, and Toyota Safety Sense. The results of this study show that partial automation has the potential to cause large increases in VMT.

Cover page of The Monetary and Non-Monetary Factors Influencing Travel Choices in an Automated, Shared, and Electric Vehicle Future

The Monetary and Non-Monetary Factors Influencing Travel Choices in an Automated, Shared, and Electric Vehicle Future


The transportation system is undergoing three revolutions: vehicle automation, electrification, and shared mobility. While these are still nascent trends, studies suggest that they could become ubiquitous in the coming decades. How these revolutionary changes transpire will have significant implications for transportation sustainability. A key factor will be whether autonomous vehicles are deployed as shared cars that serve many travelers such as in ridesourcing or ridehailing fleets, or as privately owned vehicles that could dramatically increase vehicle miles traveled and associated environmental impacts. To anticipate how these revolutions will affect future transportation, and to develop policy to shape that future, it is important to understand the various factors that influence individuals’ travel choices. These choices include whether to travel alone or with others, and whether to use a private vehicle or a shared one. Some of these factors are monetary, such as the cost of fuel, insurance, and a driver, while others are non-monetary, such as the travel time, comfort, and reliability of each transportation option. The significance of these non-monetary factors is poorly understood and often ignored.

Researchers at the University of California, Davis developed a framework for considering the monetary and non-monetary costs of future travel choices and used existing research to develop interim values for several non-monetary travel choice factors. This policy brief summarizes the findings from that research and provides policy implications.

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Cover page of Leveraging the California Highway Incident Processing System for Traffic Safety Policy and Research

Leveraging the California Highway Incident Processing System for Traffic Safety Policy and Research


Accurate data on crashes and other traffic incidents are critical for analyzing the rates, costs, and causes of crashes, and for evaluating the effects of safety policies and engineering solutions. There are two official sources of data on traffic incidents in California: 1) the Statewide Integrated Traffic Records System (SWITRS),1 managed by the California Highway Patrol (CHP), which includes post-processed data on traffic incidents leading to human injury or death; and 2) Caltrans’ Performance Measurement System (PeMS),2 which includes data on traffic incidents as well as traffic counts, lane closures, and other information. Both databases draw from CHP incident reports that describe the location, conditions, and other important details and observations surrounding each incident. Traffic safety researchers rely heavily on both databases, but each has limitations. PeMS data are limited to state highways. Incident data can take months to appear in SWITRS and may omit crucial information.

Cover page of Ten Ways Transportation Agencies Can Improve Public Engagement with Diverse Communities

Ten Ways Transportation Agencies Can Improve Public Engagement with Diverse Communities


Transportation agencies are recognizing the importance of undertaking robust public engagement, especially with historically disadvantaged communities. Many of these communities have been subject to redlining, division and demolition from highway construction or redevelopment efforts, and other forms of institutional discrimination perpetuated by civic agencies, including transportation departments. This history has fostered distrust, which makes current public engagement efforts challenging. This challenge is exacerbated by a lack of networks that might aid transportation practitioners in connecting with local residents.

Cover page of Do Electricity Prices Affect Electric Vehicle Adoption?

Do Electricity Prices Affect Electric Vehicle Adoption?


The operational costs of electric vehicles are lower than those of gas-powered vehicles. This advantage is often cited by manufacturers, advocates, and policy-makers as a significant benefit of driving electric vehicles. Yet, the question of how consumers value operational costs when purchasing an electric vehicle is largely unexplored. While prior research has suggested that gasoline prices are an important factor for conventional vehicle buyers, consumers may not have the same awareness of electricity prices as they do for salient gasoline prices. The question of whether consumers accurately assess the costs and benefits of using electricity as a transportation fuel has important implications for electric vehicle adoption and for achieving deep decarbonization of the transportation sector through electrification.

Cover page of Driving California’s Transportation Emissions to Zero

Driving California’s Transportation Emissions to Zero


California has long been a global leader in clean energy and climate policy, and it has demonstrated how industrial economies can reduce greenhouse gas (GHG) emissions while supporting strong economic growth and promoting equitable and just outcomes. In September 2018, Executive Order B-55-18 set a target for the state to achieve carbon neutrality by 2045. The University of California Institute of Transportation Studies (UC ITS) produced the first comprehensive research report analyzing the policy options that could put California’s transportation sector on a path to be carbon-neutral by 2045 while also centering equity, health, and workforce impacts. The report, summarized in this brief, presents a study conducted by 23 researchers from the four branches of the UC ITS located at UC Berkeley, UC Irvine, UC Davis, and UCLA.