policy brief

A Detailed Look at How the Pandemic Changed Travel Patterns Across Regions in Northern California Megaregion

Abstract

Many studies have focused on the shifts in travel patterns caused by the COVID-19 pandemic and how travel demand continues to evolve in the post-pandemic era. Key metrics such as trip volume–the total number of trips within a specific area–help explain the pandemic’s impact on travel demand over time. However, to fully understand changes in travel behaviors, it is also important to analyze where trips start and end—otherwise known as Origin-Destination (OD) demand.
To better understand OD demand during and after the pandemic, the research team developed a data-driven methodology to analyze travel patterns across different regions, times of day, days of the week (weekday and weekend), and trip purpose. This study used passively collected location-based data from the StreetLight Data platform (StreetLight Data, 2022) in the form of weekly OD matrices of all vehicle modes, segmented by various relevant variables. It focused on the Northern California Megaregion, which includes 21 counties from the San Francisco Bay Area to the Sacramento region and the northern part of the San Joaquin Central Valley. The study period spanned from January 2019 to October 2021.

policy brief

How Did Transit Service Adjustments During the Pandemic Impact Job Accessibility in the San Francisco Bay Area?

Abstract

This study examined geographic and temporal patterns in service adjustments and evaluated their job accessibility impacts for three major San Francisco Bay Area transit agencies between 2020 and 2023: the Alameda-Contra Costa Transit District (AC Transit), the San Francisco Bay Area Rapid Transit District (BART), and the San Francisco Municipal Transportation Agency (MUNI). This retrospective analysis can help transit agencies develop equitable service strategies in the event of future disruptions.

policy brief

Assessing the Shift to Remote and Hybrid Work in California throughout the COVID-19 Pandemic

Abstract

Beginning in 2020, many in-person activities were replaced by virtual activities as a response to the COVID-19 pandemic. This affected fundamental elements of transportation systems such as trip frequency, commute distance, origins, and destinations. For example, remote work and study were widely adopted among workers and students. Still, the ways that the pandemic affected individuals’ work arrangements across different phases of the pandemic and the extent to which full remote work and hybrid work induced by the pandemic might persist in the future are unclear. In addition, recent studies are not conclusive regarding the ways changes in work arrangements do/will impact travel patterns and trip making.

Our Experts

Recent Projects

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Research Team:

Miguel Jaller (lead), Peng Hao, Guoyuan Wu

UC Campus(es):

UC Davis, UC Riverside

Research Team:

Yongsung Lee (lead), Giovanni Circella, Miguel Jaller

UC Campus(es):

UC Davis

Our Experts

Douglas Houston

Associate Professor, Department of Planning, Policy, and Design, UC Irvine

Recent Projects

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Research Team:

Paul Ong (lead), Jacob Wasserman, Douglas Houston, Margaretta Lin, Jesus M. Barajas, Charisma Acey

UC Campus(es):

UC Berkeley, UC Davis, UC Irvine, UCLA

Research Team:

Jae Hong Kim (lead), Jesus M. Barajas, Douglas Houston, Nicholas Marantz

UC Campus(es):

UC Davis, UC Irvine

Our Experts

Recent Projects

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Research Team:

Scott Hardman (lead), Jesus M. Barajas, Weijing Wang

UC Campus(es):

UC Davis

Research Team:

Scott Hardman (lead), Alan Jenn

UC Campus(es):

UC Davis

Research Team:

Alan Jenn (lead), Scott Hardman, Aaron Rabinowitz, Yanning Li

UC Campus(es):

UC Davis

Transportation Needs for Wildfire Recovery and Resilience for Vulnerable Communities

Status

In Progress

Project Timeline

February 3, 2025

Principal Investigator

Project Team

Kailong Ji

Campus(es)

UCLA

Project Summary

Wildfires have devastating consequences for urban and rural communities. Some studies highlight limited access to alternative transportation modes for wildfire evacuation as a driving force for disparities in wildfire impacts for vulnerable communities. There are also other constraints like accessibility to evacuation centers, limited timely information, loss of cell phones, and damage to communications infrastructure. While much attention in the literature has focused on wildfire evacuation disparities tied to transportation and communications infrastructure and policy needs, there is limited focus on supporting recovery and resilience. There is a critical need to synthesize the existing knowledge for (1) safe and timely wildfire evacuations, and (2) re-entry and recovery, with emphasis on the most vulnerable and under-resourced communities.

To support recovery and resiliency efforts for the January 2025 Los Angeles wildfires, local governments and transportation agencies will require a clear understanding of transportation related drivers of disparities in wildfire impacts (for vulnerable communities relative to more affluent communities), and beyond just the evacuation stage. This project will summarize the existing knowledge on transportation and infrastructure related needs for limiting harmful impacts of wildfire and strengthening communities’ recovering from wildfire devastation. The team will review publications and available transportation and land use data on communities that have experienced wildfires to characterize their transportation infrastructure and demographic characteristics, and contrast with any variations in community recovery times.

policy brief

On-Road Motor Vehicles No Longer Dominate Ozone Formation

Abstract

The amount of traffic on California’s roadways decreased by approximately fifty percent during the COVID-19 pandemic lockdown in March and April of 2020. Conventional wisdom led to the expectation that reduced traffic would result in reduced ozone (O3) concentrations—ozone being a main component of smog—yet ozone concentrations increased during this period. Internal combustion vehicles emit oxides of nitrogen (NOx) and volatile organic compounds (VOCs). These emissions are precursors for ozone formation, but the relationship between these precursor emissions and the final ozone concentration is complex. The ratio of NOx/VOCs determines if the ozone formation will be “NOx-limited” or “NOx-rich”. Major NOx reductions are required to reduce ozone concentrations when the atmosphere is NOx-rich. Small NOx reductions in a NOx-rich atmosphere can actually increase ozone concentrations.

To inform ongoing efforts to reduce ambient O3 concentrations, this brief highlights findings from research that collected and analyzed air pollution measurements in urban locations adjacent to major freeways in the City of Sacramento and the City of Redlands—both during and after COVID-19 stay-at-home orders. The results provide an updated estimate for how many more years of NOx control will be required before O3 benefits are realized.

published journal article

Does Discretion Delay Development?

Abstract

Problem, research strategy, and findings:
Local governments sometimes approve multifamily housing through a discretionary process, meaning a public body must vote to entitle the proposal before it can seek a building permit. By-right entitlement, in contrast, allows developers to apply directly for a building permit. We tested the hypothesis that by-right approvals are faster. Faster approval can make multifamily development more feasible, which can in turn improve housing affordability. Analyses of approval pathways are often confounded by project size and complexity, but we exploited a provision in the Los Angeles Transit-Oriented Communities (TOC) program that allowed many large projects to use by-right approval. Using data from roughly 350 multifamily projects permitted in Los Angeles (CA) from January 2018 through March 2020, we compared approval timelines for both by-right and discretionary projects. We found that by-right projects were permitted 28% faster than discretionary projects, controlling for project and neighborhood characteristics. By-right projects also had less variance in their approval times, suggesting that by-right approval offers not just more speed but more certainty.

Takeaway for practice:
Planners should create more opportunities for multifamily housing to be permitted by right. Despite some selection bias in our study, evidence from the TOC program suggests that creating a by-right option would accelerate approval time and thus substantially benefit housing production. The faster approval timelines, moreover, have been accompanied by an increase in average project size and the number of units reserved for low-income households.