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.

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.

research report

Headed Out Less: Analyzing Teen and Young Adult Travel Trends in the 21st Century

Publication Date

August 4, 2025

Author(s)

Andy Fung, Fariba Siddiq, Yu Hong Hwang, Brian D. Taylor

Abstract

Since the turn of the millennium, daily travel per person in the U.S. has been declining. Leading up to the pandemic, travel by older teens and young adults declined even more steeply than among older adults. After collapsing early in the pandemic, per capita travel by all ages has rebounded, but remains below pre-pandemic levels. To explore changes in personal travel, particularly among younger travelers, we examine National Household Travel Survey data from 2001, 2009, 2017, and 2022 to compare measures of everyday travel by youth (aged 15 to 29) with middle-aged adults (aged 30 to 59). The data presented in this report point to even lower levels of youth travel compared to pre-pandemic levels. Trips for all purposes have declined in absolute terms, especially for shopping/errands and, for youth in particular, social/recreational purposes. In relative terms, private vehicle use has increased, and travel by public transit and active modes has decreased. These shifts in personal travel – down overall and toward cars – suggest that pandemic-prompted travel shifts toward fewer out-of-home activities and increased use of information and communications technologies for shopping and other trips may be having enduring effects on personal travel, particularly among younger travelers.

Steering California’s Transportation Future: A Report on Possible Scenarios and Recommendations

Status

Complete

Project Timeline

January 19, 2022 - July 14, 2022

Principal Investigator

Project Team

Jacob Wasserman, Brian D. Taylor, Juan Matute, Alejandra Rios

Campus(es)

UCLA

Project Summary

What will California’s transportation and land use future look like? Will Californians gain more mobility and housing options that support the state’s economic, social, and climate goals? Or will the car continue to shape what cities look like and how people get around in them? These questions are important because how Californians live and move in the future will be shaped by investments and policies made today. In this project, the researchers investigated the future of transportation, land use, and planning in California by exploring four transportation/land use scenarios for 2050 with a panel of 18 experts. The four scenarios were: (1) more city living and lots of traffic, (2) easy to get around without a car, (3) you’ll need a car to get around, and (4) lots of travel choices, but most will drive. Their consensus opinion was that the most desirable scenario (“Easy to Get Around without a Car”) is also the least likely to materialize, due to faults in the political planning process. Despite promising state policies to increase transportation choices, problematic local land use politics and patterns appear likely to yield a future scenario (“Lots of Travel Choices, but Most Will Drive”) that continues car dependence and chronic congestion, absent a significant rebuilding of government trust and capacity.d

Evaluating Place-Based Transportation Plans

Status

Complete

Project Timeline

September 22, 2022 - September 30, 2023

Principal Investigator

Project Team

Campus(es)

UCLA

Project Summary

California has increasingly turned to place-based, community-driven programs such as Transformative Climate Communities (TCC), the Community Air Protection Program (CAPP), and Regional Climate Collaboratives (RCC) to address the twin priorities of climate change and environmental justice. Transportation improvements are at the heart of these programs because of the potential to mitigate air pollution, greenhouse gas emissions, and inequities in access to transportation. However, these efforts are inherently difficult to evaluate as they often involve a diverse set of projects with different timelines and locations. Moreover, evaluators often face the challenge of isolating the effects of individual programs. Carefully selected control sites can support this effort, but no two communities are exactly alike, limiting the ability of evaluators to make meaningful comparisons. This research addresses how place-based climate action efforts are being evaluated, and what insights from the broader policy and plan evaluation research literature might inform evaluation design. The focus is on place-based, community-driven programs in California that encompass multiple interventions to address intertwined issues of transportation justice, climate change, and air pollution. While TCC, RCC, CAPP, and the Sustainable Transportation Equity Project (STEP) are the most high-profile programs, the project will also consider planning grants such as Sustainable Communities Planning Grants and Community-Based Transportation Plans. For each funded program site the research team will review planning and evaluation documents and annual reports to compile a dataset of data collection and evaluation activities classified by (1) type of activity being assessed (planning vs. implementation), (2) evaluation indicator (e.g. air quality, transportation accessibility), (3) data source (e.g. interviews, air sensors), and program design (e.g. cross-sectional vs. longitudinal, inclusion of control sites). The research team will complement the review of these documents with 10-20 key informant interviews with staff from state and local agencies to help understand how the evaluations are proceeding in practice, and which aspects of place-based program evaluations have proved most valuable, challenging, and scalable to other programs.