policy brief

Traffic Collisions Change How Victims Think About Safety

Publication Date

September 1, 2025

Author(s)

Md. Musfiqur Rahman Bhuiya, Jesus M. Barajas, Prashanth Venkataram

Abstract

Traffic safety remains a pressing concern in California. Over the past five years, the state has averaged more than 3,751 reported traffic fatalities annually, with likely more unreported. While policies and research often focus on crash prevention and severity reduction, less is known about how collisions affect individuals’ travel behavior and perceptions of road safety. To better understand these effects, the research team conducted interviews and focus groups with people who had direct or indirect experience with traffic collisions and near misses. The researchers also spoke with professionals who support collision victims, such as physicians, therapists, faith leaders, and advocacy groups representatives. Discussions focused on perceptions of road safety, transportation mode choices, and travel behavior of someone involved in a traffic collision or near miss before and after the incident.

published journal article

Investigating Travel Demand Heterogeneity During and After the Pandemic in the Northern California Megaregion: A Data-Driven Analysis of Origin-Destination Structural Patterns

Abstract

The study delves into the complexities of travel disruption and recovery during and after the COVID-19 pandemic. Using a data-driven methodology, we explore spatial-temporal patterns across regions by times of the day, weekdays/weekends, and trip purposes. Using passively collected location-based data from January 2019 to October 2021 in the Northern California Megaregion, our analysis compares travel patterns through the structural similarity of origin-destination (OD) matrices. Introducing the concept of a “local sliding geographical window” based on natural trip flow, the study identifies various impacts of the pandemic on travel demand including but not limited to (a) trip volume and recovery (e.g., weekday trips dropped by 47% in April 2020, gradually recovering already by October 2021); (b) impact on home-based work and other trips which were significantly disrupted on weekdays compared with non-home-based; (c) OD pattern changes (e.g., all sub-regions experienced significant changes, but the San Francisco Bay area faced the maximum disruptions); (d) gradual recovery with regional variations (e.g., San Francisco lagged in its travel activity recovery but this improved after April 2021, whereas the Northern San Joaquin Valley recovered fastest); (e) disruption and recovery linked to socioeconomic factors (e.g., parts of San Francisco, characterized by higher income, white-collar jobs, faced maximum disruption, whereas the Northern San Joaquin Valley, with a higher proportion of blue-collar workers, experienced the least disruption); and (f) differential recovery rates across and within regions, with areas rich in white-collar jobs showing slower recovery for work trips compared with areas with a higher proportion of blue-collar jobs.

published journal article

Teleworkers and Physical Commuters During the COVID-19 Pandemic: the Change in Mobility Related Attitudes and the Intention to Telecommute in the Future

Abstract

The COVID-19 pandemic has disrupted commuting habits, with many individuals shifting to telecommuting. This study examines the impact of disrupted commuting habits on psychological constructs, such as attitudes or active lifestyle. Using longitudinal survey data from the California panel study of emerging transportation, the study compares two groups (those who started telecommuting, N = 458, and those who continued physically commuting, N = 523) at two points (early pandemic 2020 and later pandemic 2021). Exploratory factor analysis was used to extract the latent psychological constructs and structural equation modeling was used to model the intention to telecommute in the future for each year. Results show that some psychological constructs (such as attitude toward sustainable modes) remain stable across groups and time, while others (such as concern about pathogens) depend on both group and stage of the pandemic. The intention to telecommute in the future remains high and is mainly dependent on individuals’ attitude toward it and their tech-savviness, rather than on a concern about pathogens or demographics. The findings may inform policies that promote sustainable and flexible mobility options, like telecommuting, that have the potential to enhance work-life balance in a post-pandemic world.

research report

Drivers’ Responses to Eco-driving Applications: Effects on Fuel Consumption and Driving Safety

Abstract

Onboard eco-driving systems provide drivers with real-time information about their driving behavior and road conditions, encouraging them to optimize their driving speed and consequently reduce fuel consumption and emissions. However, there are barriers to making eco-driving a habit. To determine the elements that influence drivers’ intentions to practice eco-driving and their acceptance of eco-driving technology, the research team developed a theoretical model based on established theories on planned behavior, technology acceptance, and personal goals. The findings showed that drivers’ intention to practice eco-driving has an indirect effect on their intention to use the system via the factor of perceived ease of use. The research team also explored how cognitive distraction while using an eco-driving system can be a potential barrier to acceptance. The intent is to put forward a solution to improve drivers’ usage of eco-driving by turning off guidance when the system detects that the driver is experiencing serious distraction. To investigate how to detect a driver’s cognitive distraction status when they are interacting with an eco-driving system, this project used a driving simulator and leveraged machine learning algorithms to classify drivers’ attentional states. The findings showed that the glance features played a more important role than the driving features in cognitive distraction.

policy brief

Women Have Smaller Activity Spaces Than Men, Especially in Households with Children

Publication Date

September 3, 2025

Author(s)

Fariba Siddiq, Zhiyuan Yao, Evelyn Blumenberg

Abstract

Differences in how men and women travel have long been a focus in transportation research. Many studies have explored how socially-defined gender roles influence travel decisions and behaviors, consistently highlighting disparities between men’s and women’s travel patterns. For example, compared to men, women tend to make more caregiving and household-related trips, have shorter commutes, and are more likely to combine multiple destinations or purposes into a single tour. This body of research often concentrates on standard measures of travel—such as the number of trips taken, how far and for how long people travel, and travelers’ experiences— while also considering the influence of neighborhood design. However, travel patterns also are shaped by broader social structures and inequalities, which are not captured by these traditional measures. To better understand sex differences in travel, this study examined disparities in the size of an individual’s “activity spaces,” defined as the geographic area a person covers during daily activities, such as commuting, shopping, socializing, and leisure. The study draws on detailed trip data from the confidential California add-on to the 2017 National Household Travel Survey (NHTS), which provides the exact starting and ending locations for each trip taken on the survey day. The study estimates the size of each person’s activity space and compare patterns between men and women. It then explore how these differences relate to individual, household, and neighborhood characteristics.

policy brief

Advancing Community-Identified Strategies to Transform Roadways in California’s San Joaquin Valley

Abstract

Disparities in exposure to roadway hazards (e.g., pollution, noise) remain stubbornly persistent due to structural inequalities embedded in the built environment. Research has consistently documented racial/ethnic and socioeconomic disparities in traffic exposures nationwide, including heightened exposure to heavy-duty truck traffic, a significant source of noise and pollution. Such disparities also exist in the provision of sidewalks, bike lanes, and street trees, which can help mitigate roadway dust, noise, and pollution and can increase pedestrian safety, encourage walking and cycling, and provide health benefits.

This publication describes how the research team evaluated opportunities and barriers to using a community steering committee process approach to advance environmental justice and transportation equity. Through interviews and case study analysis, the team examined the role community leaders played in the prioritization and implementation of three community-identified strategies that mitigate roadway hazards in three AB 617 communities in California’s San Joaquin Valley – Stockton, South Central Fresno, and Arvin/Lamont. These strategies include (1) vegetative barriers between roadways and sensitive land uses; (2) expanded sidewalk infrastructure; and (3) revised heavy duty truck route designations.

research report

Between the Forest and the Trees: Community Strategies to Transform Roadways in California’s San Joaquin Valley

Abstract

Expanding participation of historically disenfranchised groups within decision-making processes is an important strategy to increase equity within transportation planning but traditional engagement practices (e.g., public meetings, focus groups) have historically done little to address the needs of disadvantaged communities. This study evaluates the opportunities and barriers to using a community steering committee participation model within transportation planning to advance equity and environmental justice. It utilizes interview and case study analysis to examine the experiences of residents and community leaders in prioritizing community-identified strategies to mitigate roadway hazards in three AB 617 communities in California’s San Joaquin Valley – Stockton, South Central Fresno, and Arvin/Lamont. It investigates the role resident and CBO members played in the prioritization, approval, and implementation of three strategies to transform roadways and mitigate air pollution, noise, dust, and safety hazards: (1) new vegetative barriers between major roadways and sensitive land uses; (2) expanded sidewalk infrastructure; and (3) revised heavy-duty truck route designations. Findings demonstrate that “meaningful involvement” for impacted communities within transportation planning will require officials, residents, and organizations to commit to an ongoing process of experimentation and learning about the most effective approaches for advancing transportation equity and environmental justice.

Impacts of Remote/Hybrid Work and Remote Services on Activity and Transportation Patterns

Status

In Progress

Project Timeline

May 1, 2025 - March 31, 2026

Principal Investigator

Campus(es)

UC Davis

Project Summary

This project will provide science‐based robust information on the behavioral impacts of information and communication technology (ICT) based remote activities on travel choices, including telework, hybrid work, and online shopping. The study will analyze data from the California Mobility Panel, which has been built with rounds of data collection in 2018, 2019, spring and fall 2020, 2021, and 2023, and will be complemented by a new round of data collection in fall 2024. With unique, rich panel data, the project will model complex relationships around remote activities in a single modeling framework, which examines cross‐domain and bidirectional causal effects. The project will employ robust analytical approaches to estimate the effects of remote activities on travel patterns under different land use configurations. The project will greatly improve the understanding of the impacts of remote/hybrid work and other remote services and inform State and planning agencies by shedding light on the complex ways remote activities affect short‐term daily routines (e.g., telecommuting vs. commuting trips, travel mode choice, and spatial/ temporal trip distributions) and long‐term choices (vehicle choice, residential location and real estate development), and will help understand the impacts on vehicle miles traveled (VMT) and transportation‐based greenhouse gas (GHG) emission impacts.

policy brief

What Would it Take for Drivers to Adopt Eco-Driving Behaviors?

Abstract

Climate change in California could greatly impact the state’s economy, nature, and public health. One strategy to reduce fuel consumption and greenhouse gas emissions from the transportation sector is eco-driving. Eco-driving is a set of behaviors or driving styles that encourage fuel-efficient driving that could help minimize energy consumption anywhere from five to 30 percent. With the advance of connected-vehicle technologies, the dynamic eco-driving concept uses real-time vehicle-specific information to optimize vehicle speed and reduce fuel consumption and emissions.

This policy brief finds that driver motivations for adopting eco-driving behaviors varies, perceived ease of use was a key factor influencing a
driver’s intention to use an eco-driving system, and (3) based on the result of the driving simulator experiment, drivers may become distracted while trying to follow the information provided by the eco-driving interface.

Investigating the Evolution of Residential Self-Selection in the Post-COVID Era: The Transition to Digital Lifestyles and Changing Travel Behaviors

Status

In Progress

Project Timeline

May 1, 2025 - June 30, 2026

Principal Investigator

Basar Ozbilen

Project Team

Campus(es)

UC Davis

Project Summary

The COVID-19 pandemic has caused a profound transformation in individuals’ residential location choices and travel patterns. Traditional determinants of where to live, such as housing affordability or proximity to work/amenities, now closely intersect with the convenience of remote work and other online activities. This transition reshapes how individuals choose their living environment and organize their travel during the day. To navigate this evolving landscape, this research will delve into the residential self-selection in the post-COVID era. Central to the researchers’ investigation is understanding individuals’ shifting tendencies towards digital nomadism and the impact of this transition on housing preferences and activity-travel behavior. The researchers seek to uncover to what extent factors like the convenience of remote activities, hybrid work schedules, and tech-savviness influence residential and travel choices. Furthermore, the researchers will explore the equity considerations inherent in these decisions, examining how sociodemographics intersect with the evolving structure of residential self-selection. To achieve these objectives, the researchers will employ a targeted sampling methodology to recruit individuals who have relocated over the last 12 months, as well as those who have not moved since the start of the pandemic in March 2020. Through the analysis of this dataset that consists of movers and non-movers, the researchers will have the opportunity to (1) track the factors impacting relocation decisions and those influencing residential stability, (2) explore the effects of the remote activities both on residential and travel choices, and (3) assess the differences in remote activity participation and residential location choice across various population segments. These findings will not only inform planning and policy decisions but also set a baseline for future studies focusing on the interplay between residential self-selection, digital lifestyles, and housing preferences.