research report

Effects of Road Collisions on the Travel Behavior of Vulnerable Groups: Expert Interview Findings

Abstract

The research team interviewed eight subject-matter experts in California in 2023 to understand how travel behavior and priorities may change in response to direct experience with road collisions. Experts represented a variety of perspectives, including medical doctors, advocates for active transportation safety, and advocates for people with disabilities. Their diverse specialties enabled us to capture a variety of concerns without triggering emotionally sensitive areas for people who have directly experienced road collisions. These experts identified common themes, including mental stress from the prospect of returning to driving—especially on freeways, lesser incidence of long-term changes in travel modes after experiencing a collision, dependence on others for rides in private vehicles, and changing routes or times of day of travel when traveling independently. These experts also explained how people’s mode choices are also affected by general concerns about collisions in the news more than by specific personal experiences with near misses. Interview subjects’ spoke of more specific concerns as well. These included but were not limited to, bicyclists using sidewalks instead of bike lanes when both are present, feeling stigmatized from using public transit or paratransit after experiencing a collision, and concerns with motorists treating bicyclists badly. These initial interviews clarify areas of focus and methodology for future qualitative and quantitative studies on the intersection of transportation safety and travel behavior change, particularly as they involve people who have directly experienced road collisions.

research report

An Integrated Corridor Management for Connected Vehicles and Park and Ride Structures using Deep Reinforcement Learning

Abstract

The upcoming Connected Vehicles (CV) technology shows great promise in effectively managing traffic congestion and enhancing mobility for users along transportation corridors. Data analysis powered by sensors in Connected Vehicles allows us to implement optimized traffic management strategies optimizing the efficiency of transportation infrastructure resources. In this study, the research team introduces a novel Integrated Corridor Management (ICM) methodology, which integrates underutilized Park-And-Ride (PAR) facilities into the global optimization strategy. To achieve this, the team uses vehicle-to-infrastructure (V2I) communication protocols, namely basic safety messages (BSM) and traveler information messages (TIM) to help gather downstream traffic information and share park and ride advisories with upstream traffic, respectively. Next, the team develops a model that assesses potential delays experienced by vehicles in the corridor. Based on this model, the research team employs a novel centralized deep reinforcement learning (DRL) solution to control the timing and content of these messages. The ultimate goal is to maximize throughput, minimize carbon emissions, and reduce travel time effectively. To evaluate the Integrated Corridor Management strategy, the paper includes simulations on a realistic model of Interstate 5 using the Veins simulation software. The deep reinforcement learning agent converges to a strategy that marginally improves throughput, travel speed, and freeway travel time, at the cost of a slightly higher carbon footprint.

preprint journal article

Patterns in Bike Theft and Recovery

Publication Date

September 1, 2023

Author(s)

Dillon Fitch-Polse, David Nelson, Achituv Cohen, Trisalyn Nelson, Lizzy Schattle

Abstract

Our goal is to reduce the negative impacts of bicycle theft by better understanding patterns in bicycle theft and recovery. The research team analyzed data from 1823 responses to a North American survey on bicycle theft conditions, recovery circumstances, and demographics. Survey recruitment was done in partnership with BikeIndex, a non-profit bicycling registration service. Most bikes were stolen from inside a shed or garage (28%) or from outdoor bicycle racks (18%) and most thefts occur overnight (41%). 15% of stolen bicycles were recovered. Key factors in recovery include police involvement, bike registration, and reporting the theft through multiple channels.

published journal article

Crabgrass confinement: Housing and transportation challenges of low- and moderate-income suburban residents in the San Francisco Bay Area

Abstract

The relationship between housing and transportation costs has been the focus of much research, with classic urban theory positing that housing costs decrease and commuting costs increase as households move away from city centers. The growing population of low and low-moderate (LMI) households in suburbs may be taking advantage of lower housing costs, though research shows that housing cost savings in suburbs are offset by higher transportation costs. Our research explores dimensions of housing and transportation cost burden on LMI households in Contra Costa County in the San Francisco Bay Area using qualitative data from online/in-person surveys (n = 208) and interviews conducted in English and Spanish (n = 25).

We found that the housing burden is high, suggesting that LMI households choose to live in the suburbs for diverse reasons, including rising rents and other requirements (e.g., credit score, rental history) in core cities, and desire for home ownership and a safer environment for children. Yet LMI suburban residents are still vulnerable to rising rents and housing instability in suburban areas. In addition to high housing costs, transportation costs are higher in suburbs due to longer commutes and higher reliance on personal vehicles. Car access is necessary, especially for households with young children. Reliance on cars becomes an issue as LMI households often encounter maintenance issues with used cars or the inability to make car payments. When faced with a lack of car ownership, households rely on social networks or public transit, and in some cases, forgo trips or relinquish their vehicles entirely. The lack of quality transportation alternatives in suburban contexts, as existing public transit services, have long headways and are not well-suited to serving off-peak trips between suburban areas, leaves LMI households vulnerable.

research report

Stockton’s Crosstown Freeway, Urban Renewal, and Asian Americans: Systemic Causes and Impacts

Abstract

This project uses mixed methods to examine the systemic causes and consequences of the construction of Stockton, California’s Crosstown Freeway, and urban redevelopment for Asian American communities. Stockton underwent spatial restructuring in the decades after the Second World War, and state and local governments contributed and responded to these changes by implementing connected freeway and urban renewal programs. Historical and contemporaneous xenophobia and racism placed Chinatown, Japantown, and Little Manila in their path, with these enclaves deemed blighted and subject to “slum clearance.” The choice of freeway route was racially biased. The neighborhood surrounding an unchosen route was predominantly white, whereas that of the chosen route was predominantly home to people of color. Freeway construction during the 1960s and 1970s directly displaced hundreds of people and housing units downtown— mainly people of color, particularly Asians. The communities most harmed were the Asian American enclaves, where the housing stock declined by about three-quarters between 1960 and 1970. The losses were not only physical, as the freeway and redevelopment eviscerated once vibrant ethnic commercial hubs. Because of long-standing economic and political marginalization, Asian Americans were relatively powerless to prevent the destruction; nonetheless, they fought to build affordable housing for their people, protect and in some cases relocate cultural institutions, and support surviving ethnic businesses. In the long run, Stockton failed to revitalize its downtown, while destroying its cultural diversity. The findings can help reform and improve professional practice within the transportation arena to ensure racial fairness and equity.

op-ed

How California can use electric vehicles to solve its blackouts

published journal article

Transit’s Financial Prognosis: Findings from a Survey of U.S. Transit Systems during the COVID-19 Pandemic

Abstract

The COVID-19 pandemic occasioned significant financial distress and uncertainty for many U.S. transit operators. In the face of this crisis, the federal government provided substantial supplemental operating support. To understand how this fiscal turmoil and relief have affected U.S. transit systems, we conducted two nationwide surveys of transit agency staff in 2020 and 2021-2022. While pandemic-induced financial shortfalls affected service in 2020, with capital projects delayed too, these effects became much more muted by 2021/2022. Most systems reported moderate to substantial increases in federal funding during the pandemic, more so than other funding categories. However, nearly half foresee financial shortfalls once federal relief funding expires. Agencies with higher pre-pandemic ridership and farebox recovery are particularly affected by fare revenue losses and are more likely to anticipate shortfalls. In the near term, difficulty hiring and retaining front-line workers was a pressing concern, while very few had plans to maintain pandemic fare suspensions.

blog

Transit Ridership at Bay: Reflections on the UCLA ITS Bay Area Transit Use Study