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.

research report

Learning to Collaborate: Lessons Learned from Governance Processes Addressing the Impacts of Sea Level Rise on Transportation Corridors Across California

Abstract

This study was designed to identify lessons learned from experiences of multi-stakeholder collaboration in governance processes focused on adaptation to sea level rise for specific transportation corridors/assets across different areas of California. Four transportation assets in California were selected as case studies: State Route 37 in the Bay Area; the Cardiff Beach Living Shorelines Project and the LOSSAN railroad at Del Mar in San Diego County; and the Port of Long Beach in Los Angeles County. The study methods included attendance of policy meetings; document analysis; and interviews of staff at (local, regional, and state) government bodies, transportation agencies, climate collaboratives, etc. The study identified three major governance challenges shared among these cases: (1) stakeholder involvement or collaboration with ‘unusual’ partners; (2) jurisdictional fragmentation; and (3) lack of funding. The lessons learned to address these challenges were: (a) include a wide range of stakeholders early on in the project; (b) identify an intermediary or facilitator with relevant knowledge and social capital with the stakeholders; (c) establish a forum for negotiations and information exchange; (d) draft a memorandum of understanding with the rules of collaboration; (e) appoint a project manager to tie all the project parts and stakeholders together and sustain engagement; (f) structure the collaboration in tiers from technical/operational to executive/political; (g) explore options to make any given project a multi-benefit project; (h) advocate for a multi-year stream of funding rather than a lump sum; (i) leverage collaboration for funding and highlight, to potential funders, the collaborative element as a means to increase the efficiency of their investment. Issues to consider when deriving lessons from other jurisdictions were: differences in capacity, or available resources and staff; the numbers of actors involved; pre-existing positive collaborative relationships between the actors; exposure of transportation assets to sea-level rise; existing vulnerabilities of the corridor/asset; and the economic relevance of the corridor/asset.

research report

Research Synthesis for the California Zero Traffic Fatalities Task Force

Abstract

This research synthesis consists of a set of white papers that jointly provide a review of research on the current practicefor setting speed limits and future opportunities to improve roadway safety. This synthesis was developed to inform thework of the Zero Traffic Fatalities Task Force, which was formed in 2019 by the California State Transportation Agencyin response to California Assembly Bill 2363 (Friedman). The statutory goal of the Task Force is to develop a structured,coordinated process for early engagement of all parties to develop policies to reduce traffic fatalities to zero. Thisreport addresses the following critical issues related to the work of the Task Force: (i) the relationship between trafficspeed and safety; (ii) lack of empirical justification for continuing to use the 85th percentile rule; (iii) why we need toreconsider current speed limit setting practices; (iv) promising alternatives to current methods of setting speed limits;and (v) improving road designs to increase road user safety.

research report

Transportation, Quality of Life, and Older Adults

Abstract

Driving rates decline with age as vision, health, and cognitive ability cause some older adults to give up driving. Many older adults first gradually limit their driving as they age and later cease driving. Using data from the Health and Retirement Study (HRS), which surveys 22,000 older Americans every two years, the research team modeled the extent to which older drivers limit and stop driving. The data are longitudinal, allowing analysis of changes in driving and residential location as well as cohort effects that could not be studied using standard, cross-sectional survey data that only allow comparisons of different people at one point in time. The analysis shows that decisions to limit and eventually stop driving vary in statistically significant ways with sex, age, and health conditions. These relationships also differ by birth cohort. More recent cohorts are less likely to stop and limit driving than older ones. To analyze the relationship between residential location and driving behavior, the team linked the HRS data to census-tract-level data from the US Census and a categorization of community types. The research team found that residential density and other features of urban built environments are associated with changes in driving and vehicle ownership. HRS survey participants showed a greater propensity to reduce or give up driving if they resided in denser, more diverse, transit-oriented neighborhoods. People who prefer non-automotive modes of transportation may have been more likely than others to self-select into walkable and transit-rich areas. The findings should inform California’s strategic planning for aging and its community development policies. In addition to informing planning for the next generation of older Californians, this study demonstrated the utility of longitudinal information and models for the understanding of older populations and their travel.

research report

Supercharged? Electricity Demand and the Electrification of Transportation in California

Abstract

The rapid electrification of the transportation fleet in California raises important questions about the reliability, cost, and environmental implications for the electric grid. A crucial first element to understanding these implications is an accurate picture of the extent and timing of residential electricity use devoted to electric vehicles. Although California is now home to over 650,000 electric vehicles (EVs), less than 5% of these vehicles are charged at home using a meter dedicated to EV use. This means that state policy has had to rely upon very incomplete data on residential charging use. This report summarizes the first phase of a project combining household electricity data and information on the adoption of electric vehicles over the span of four years. The research team proposes a series of approaches for measuring the effects of EV adoption on electricity load in California. First, the team measures load from the small subset of households that do have an EV-dedicated meter. Second, the paper estimates how consumption changes when households go from a standard residential electricity tariff to an EV-specific tariff. Finally, the research team suggests an approach for estimating the effect of EV ownership on electricity consumption in the average EV-owning household. The team implements this approach using aggregated data, but future work should use household-level data to more effectively distinguish signal from noise in this analysis. Preliminary results show that households on EV-dedicated meters are using 0.35 kWh per hour from Pacific Gas and Electric (PGE); 0.38 kWh per hour from Southern California Edison; and 0.28 kWh per hour from San Diego Gas and Electric on EV charging. Households switching to EV rates without dedicated meters are using less electricity for EV charging: 0.30 kWh per hour in PGE. The household approach applied to aggregated data is too noisy to be informative. These estimates should be viewed as evidence that a more focused analysis with more detailed data would be of high value and likely necessary to produce a rigorous analysis of the role EVs are playing in residential electricity consumption.