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Open Access Publications from the University of California

Recent Work

The Transportation Sustainability Research Center fosters research, education, and outreach so that transportation can serve to improve economic growth, environmental quality and equity. Co-Directors are Dan Kammen, the Class of 1935 Distinguished Professor of Energy at UC Berkeley, Tim Lipman, PhD, and Susan Shaheen, PhD. The groups participating in this effort are the:

University of California Transportation Center
University of California Energy Institute
Institute of Transportation Studies
Energy and Resources Group
Center for Global Metropolitan Studies
Berkeley Institute of the Environment

Cover page of Advanced Air Mobility: Opportunities, Challenges, and Research needsfor the State of California (2023-2030)

Advanced Air Mobility: Opportunities, Challenges, and Research needsfor the State of California (2023-2030)

(2024)

Advanced air mobility (AAM) is a broad concept that enables consumers access to air mobility, goods delivery, and emergency services through an integrated and connected multimodal transportation network. AAM can provide short-range urban, suburban, and rural flights of about 50-miles and mid-range regional flights up to a several hundred miles. State law delegates responsibility for oversight in aviation primarily to the California Department of Transportation (Caltrans). This white paper presents an overview of the state of the market, such as the aircraft under development and forecast market growth and discusses factors that could facilitate the development of AAM or pose risks to its deployment or to the public, including the safety and the regulatory environment, airspace and air traffic management, security, environmental impacts, weather, infrastructure and multimodal integration, workforce and economic development, social equity, and community engagement and social acceptance. It concludes by recommending actions that Caltrans and other state agencies can take to facilitate the development of AAM.

Cover page of Going My Way? Understanding Curb Management and Incentive Policies to Increase Pooling Service Use and Public Transit Linkages in the San Francisco Bay Area

Going My Way? Understanding Curb Management and Incentive Policies to Increase Pooling Service Use and Public Transit Linkages in the San Francisco Bay Area

(2023)

Despite lower user costs, only 20% to 40% of transportation network company (TNC) users select a pooled, or shared, ride option. Why are existing TNC users not selecting the pooled option or using TNCs to connect to public transit, and what role do built environment features and incentives play in their decision? This study explores the factors that influence TNC user decisions through a multi-method approach comprising photovoice small group discussions and a workshop. Between March 2021 and May 2021, 15 San Francisco Bay Area TNC users shared photographs they took of TNC pick-up locations through two-to-three-person guided small group discussions. The photos revealed that users prefer waiting in retail or in well-lit, good-visibility locations. Participants’ primary concern was personal safety, particularly female users who may take additional precautions when walking to pick-up locations and waiting for and taking rides. In July 2021, 12 photovoice participants and 5 stakeholders provided feedback on key findings from the photography discussions. The pooling improvement strategies identified include the following: designated TNC stops with lighting and marked pick-up areas; enhanced in-app safety features; TNC partnerships with employers and retailers to incentivize riders; and mode transfer discounts for connecting TNCs to public transit. The findings suggest that safety related to the built environment plays an outsized role in a TNC user’s decision to pool or connect to public transit, and the out-of-vehicle portion of the TNC trip should be equally considered when developing policies to increase pooling.

Cover page of Creative Reallocation of Curbs, Streets, Sidewalks Accelerated by the Pandemic May be Here to Stay

Creative Reallocation of Curbs, Streets, Sidewalks Accelerated by the Pandemic May be Here to Stay

(2023)

Curb space has been traditionally designed for private vehicle parking, public transit, and passenger and commercial loading. However, in recent years, a growing number of newservices and activities have increased the demand for limited curb space, including passenger pick-up and drop-off; last-mile delivery (e.g., courier network services, personal delivery devices); electric vehicle (EV) charging; micromobility parking and use (e.g., personally owned and shared bikes and scooters); and carsharing services. The curb serves a variety of functions such as vehicle and device storage (including personally owned and shared vehicles and devices), outdoor dining and retail, greenspace, and other uses. These changes are contributing to a notable shift in how people access and use the curb, and how public agencies plan, prioritize, and manage curbside interactions.

Cover page of Do Incentives Make a Difference? Understanding Smart Charging Program Adoption for Electric Vehicles

Do Incentives Make a Difference? Understanding Smart Charging Program Adoption for Electric Vehicles

(2023)

Climate change and environmental problems have spurred new strategies to reduce fossil fuel consumption in transportation. Two important strategies include a rapid transition to green energy and the replacement of internal combustion vehicles with electric vehicles (EVs). However, the increasing demand for electricity by EVs, especially from time-dependent green sources of energy (e.g., solar, wind), will likely overload the grid at peak hours. Rather than build costly infrastructure improvements for distribution and generation, smart charging programs for EVs could defer charging to off-peak times and better match demand with supply. Yet, little is currently known about people’s willingness to participate in a program and relinquish control of charging to a third party.

Cover page of Transportation Network Companies Might Be Pulling Riders from Public Transit, but This Could Change

Transportation Network Companies Might Be Pulling Riders from Public Transit, but This Could Change

(2023)

Transportation Network Companies (TNCs, also known as ridehailing and ridesourcing) have expanded across California over the past decade and changed the way people travel. Using a smartphone, travelers can quickly summon a vehicle from almost anywhere and know what the estimated wait time, travel time, and cost will be before stepping into the vehicle. While TNCs are clearly addressing an unmet need for travelers, their growing popularity has raised a number of policy questions, including if TNCs are shifting people away from public transit and other travel modes (e.g., carshare, walking, biking).

Cover page of Zero-Emission Bus Implementation Guidebook for California Transit Fleets

Zero-Emission Bus Implementation Guidebook for California Transit Fleets

(2023)

Transit bus operations in California are experiencing new challenges due to economic conditions and the ongoing global pandemic. A confluence of factors has created a focus on this critical public-needs serving industry, due to state and local efforts to reduce emissions of pollutants and climate-changing gases. Transit bus operations in California provide essential and additional useful services that offer critical mobility to needy populations (elderly and handicapped) as well as many other groups for whom transit buses provide the most economical, convenient, and low-emission options. To address the role of transit bus operations in meeting California’s aggressive greenhouse gas (GHG) and emissions, the California Air Resources Board (ARB) has implemented an ambitious Innovative Clean Transit (ICT) regulation that requires all public transit agencies to gradually transition to a 100 percent zero-emission bus (ZEB) fleet.1 Beginning in 2029, 100% of new purchases by transit agencies must be ZEBs, with a goal for a full transition by 2040. Prior to that 25% of purchases of new buses must be ZEBs in 2023-2025 for large transit agencies, rising to 50% in 2026-2028. For smaller transit agencies, defined as those with less than 100 buses in annual maximum service, there is no requirement for 2023-2025 and the requirement for 2026-2028 is 25%, but the 100% ZEB purchase requirement starting in 2029 applies to all agencies.

Cover page of Future of Aviation: Advancing Aerial Mobility through Technology, Sustainability, and On-Demand Flight

Future of Aviation: Advancing Aerial Mobility through Technology, Sustainability, and On-Demand Flight

(2023)

Advanced air mobility (AAM) is a broad concept enabling consumers access to air mobility, cargo and package delivery, healthcare applications, and emergency services through an integrated and connected multimodal transportation network. AAM includes local use cases of about a 50-mile radius in rural or urban areas and intraregional use cases of up to approximately 500 miles that occur within or between urban and rural areas. The Future of Aviation Conference: Advancing Aerial Mobility through Technology, Sustainability, and On-Demand Flight was held in person at the San Francisco International Airport from August 2 to 5, 2022. The conference commenced with an AAM 101 workshop hosted by the Community Air Mobility Initiative (CAMI) on August 2nd. The full conference program began on August 3rd. This event advanced key research and policy discussions around environmental impacts, safety, security, equity, multimodal integration, and the role of government.

Cover page of Advancing Road User Charge (RUC) Models in California: Understanding Social Equity and Travel Behavior Impacts

Advancing Road User Charge (RUC) Models in California: Understanding Social Equity and Travel Behavior Impacts

(2022)

The State of California is currently moving forward with a road usage charge (RUC) demonstration program, creating promising research opportunities to examine the potential social equity implications of a shift from a gas tax to a RUC system in California. RUC . To this aim, this study investigates the relative burden of gas taxes and mileage-based RUC across various sociodemographic and geographic dimensions by examining key trends in road use, vehicle ownership, fuel consumption, use of RUC-related technologies, and attitudes/opinions related to RUC adoption. Expert interviews were conducted to increase understanding of the potential opportunities and challenges of a RUC system, particularly regarding social equity. The interviews included transportation industry professionals as well as representatives from community-based and other stakeholder organizations to understand best practices for RUC design and implementation, identify stakeholders’ concerns and potential ways to address them, and inform the design and analysis of a survey of Californians.