Understanding the Current State of, Changes in, and Decision-Making on Responses to Homelessness on State Transportation Lands

Status

In Progress

Project Timeline

October 1, 2026 - September 30, 2027

Principal Investigator

Project Team

Jacob Wasserman, Hao Ding

Campus(es)

UC Irvine, UCLA

Project Summary

More than 185,000 Californians and over three-quarters of a million Americans experience homelessness every night. The limited capacity of shelters and social service agencies to meet the needs of this rapidly growing population has forced many to look for shelter in state transportation settings. Living close to freeways is dangerous for people experiencing homelessness. With affordable housing scarce and the crisis often overwhelming existing safety nets, state departments of transportation (DOTs) face these pressing issues. This research project will answer: 1) how do state DOTs comparatively perceive and respond to homelessness on their lands, 2) how have the characteristics of homelessness in state transportation settings and responses to it changed over time, and 3) what factors influence decision-making in DOT homelessness response? The researchers will first explore the results of already completed but not yet analyzed surveys of state DOTs and of Continua of Care (regional homelessness authorities). The team will also conduct interviews and review available documents and data to update and critically examine the activities of Caltrans in response to homelessness and their changes over time. Finally, the researchers will draw on case studies of responses elsewhere, examples of which can be adapted in California and beyond.

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published journal article

Constrained Choices: Rethinking the Assumption of Choice in Auto Ownership Modeling to Advance Equity

Abstract

The rapidly-evolving landscape of transportation technologies requires that we re-examine our transportation modeling tools and their ability to reflect the likely impacts of these technologies across society. Traditional auto ownership models, among other components of travel demand models, are designed based on the assumptions that one’s transportation alternatives are known and deterministic. However, this assumption is in tension with decades of empirical evidence that documents the influence of various constraints on decision making. Further, the effects of these constraints on choice outcomes, may vary systematically; access to a given transportation alternative within the choice set may be tied to a set of decision-maker characteristics.
In this study, the researchers implement a choice set formation model framework to measure potential variations in auto ownership outcomes, with emphasis on constrained travelers. The model specifications test various factors that have been found in past empirical studies to influence households’ ownership choice alternatives, including financial constraints. Results show that the choice set formation model specification with constraint variables offers improvements in model performance, particularly for constrained subgroups, relative to the conventional model specifications. The choice set formation model offers reductions in prediction error rates, with 37% and 29% lower error rates for Black households and households with lower educational attainment, respectively.
These results demonstrate the reality of considerable differences in model performance across subgroups. While further study is warranted to understand implications for transportation demand modeling practices, this article argues that the use of conventional model specification may result in harmful consequences for constrained travelers when their travel behaviors and outcomes are poorly captured or distorted.

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published journal article

Between the Forest and the Trees: Navigating Silos and Setbacks to Vegetative Roadway Barriers

Abstract

Expanding participation of marginalized groups within decision-making could help address environmental injustice and increase equity. This article assesses the potential and challenges of expanded engagement by examining community steering committee (CSC) processes of three communities in the San Joaquin Valley participating in California’s Assembly Bill 617 program to engage local stakeholders to mitigate pollution hotspots. Researchers use case study and interview analysis to assess CSC resident experiences prioritizing, approving, and monitoring implementation of one community-identified strategy: the installation of vegetative barriers (VB) between hazardous facilities (e.g., freeways) and sensitive uses to mitigate pollution exposure. Although residents successfully directed substantial funding toward community-identified VB priorities, the researchers find that the scale of adopted VB projects was modest relative to resident aspirations for a more robust, community-wide protective VB network. Findings point to the opportunities and challenges of using a steering committee model to integrate impacted residents into emissions reduction planning processes.

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research report

Comparison of Low-Carbon Transport Strategies in California and Europe

Abstract

A rapid transition to a near-zero-emission transportation system in California and Europe will require rapid uptake of transportation technologies, changes in transportation services, and investments in associated infrastructure. These in turn require policy innovations. This report compares California and EU policies across three broad areas: 1) greenhouse gas (GHG) targets for 2030 to 2050; 2) progress on reducing GHG emissions from different transportation modes; and 3) current strategies and policies to achieve targets. Differences by region and across major modes are identified. Strategies cover electrification, uptake of hydrogen, aviation and shipping fuels, and modal shifts. Policies include regulatory requirements (fuel economy and CO2 standards, fuel standards); incentive programs, including taxation, feebates, and others; direct investment programs; equity considerations and environmental justice-related initiatives. In both geographies, a range of impactful policies are in place. However, these fall short of guaranteeing that targets will be met, and more actions will likely be needed. Some possibilities are presented, with a particular focus on pricing strategies.

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

Status

Complete

Project Timeline

October 1, 2022 - September 30, 2023

Principal Investigator

Prashanth Venkataram

Project Summary

The last five years in California have seen annual averages of over 3,800 fatalities, nearly 15,900 serious (but not fatal) injuries, and over 233,100 minor injuries from vehicular collisions. These collisions disproportionately occur in marginalized neighborhoods and victimize people from socioeconomically marginalized groups, including people with disabilities. Despite the physical injuries and mental traumas that collisions can inflict upon victims, loved ones, emergency responders, and even otherwise unrelated bystanders, little is known about the effects of collisions on their travel behavior, such as frequency of travel and mode choices. Hypothetically, decreases in travel frequency could significantly harm socioeconomic equity, as victims or loved ones who travel less may participate less in the economy as workers or consumers, and these effects may be amplified for people with disabilities, who already face disadvantages with respect to access and mobility. Additionally, changes in mode choices, especially away from public or active transportation toward private vehicular transportation, may undercut Caltrans’s connected goals for road safety, equity, and greenhouse gas emission reduction in the California Transportation Plan 2050, Caltrans 2020-2024 Strategic Plan, and California 2020-2024 Strategic Highway Safety Plan. This study aims to answer: (1) How do experiences with collisions or near misses affect travel frequencies and mode choices among people with disabilities? (2) Do experiences with collisions or near misses correlate with people being less likely to use certain vehicular modes (e.g., driving, riding as a passenger, or using taxis, ridehailing services, or paratransit) compared to those without such experiences? To answer these questions, this project will use informal interviews, focus groups, and a survey. The research team will work with community-based organizations (CBOs) throughout California, especially those that advocate for people with disabilities, who are disproportionately vulnerable to collisions, as well as those which advocate for road safety in socioeconomically marginalized communities. Informal interviews and focus groups with representatives from those CBOs will help the researchers better understand issues facing people experiencing collisions and near misses, what questions may be too sensitive or problematic to ask such people, and policy challenges. Following these discussions, the research team will survey adults in California about their current frequencies of using different modes of transportation, firsthand or secondhand experiences with collisions or near misses, the extent to which those experiences have influenced their mode choices, their neighborhood type, and demographic, socioeconomic, and disability status. Findings will contribute to formulating policies for roadway safety, transportation equity, and greenhouse gas emission reduction.

Collection of Activity Data from On-Road Heavy-Duty Diesel Vehicles

Status

Complete

Project Timeline

August 1, 2016 - July 31, 2017

Principal Investigator

Kanok Boriboonsomsin

Project Summary

A selective catalytic reduction (SCR) after treatment system on 2010-technology heavy-duty diesel vehicles reduces oxides of nitrogen (NOX) emission in the exhaust stream, but requires adequate temperature, typically at least 200°C, for the reduction to take place. However, there are times when this temperature requirement is not met, such as initial engine start and during low load operations experienced when the vehicle is idling or moving slowly to meet various vocational demands. To better quantify real-world NOx emissions achieved by SCR, it is thus critical to characterize heavy-duty diesel vehicle vocation-specific activity profiles, including duty cycles, number of engine starts, SCR temperature profiles, and engine soak time distributions. The project team recruited and collected instantaneous location and engine activity data for a minimum of 4 weeks for each of 90 heavy-duty vehicles with gross vehicle weight ratings (GVWR) of 26,000lbs or higher. Eight of the 90 vehicles were not equipped with SCR after treatment systems: five express buses powered by natural gas and three diesel trucks older than the 2010 model year. A total of 19 vocation types were identified, covering a range of vocational uses, GVWR, and geographic regions. Activity profiles of idling, diurnal distribution of activity, trips per day, soak time distribution, SCR temperature profiles, and characteristics of driving cycles were characterized for each vocation type. These activity profiles are extremely important for improving the heavy-duty NOx emission inventory and estimating the frequency of good SCR function.

Towards More Credible VMT Forecasts for Project-Level Analysis in California

Status

In Progress

Project Timeline

June 1, 2026 - June 30, 2028

Principal Investigator

Campus(es)

UC Berkeley, UC Davis, UCLA

Project Summary

Much of California’s sustainability policy is premised on the idea of reducing Vehicle Miles Traveled (VMT). Under current state law, development projects cannot be approved without first estimating how much VMT they are likely to create, and then (often) taking steps to mitigate that VMT. The obstacle California faces, for this regulatory regime to be successful, is one of accounting. It remains hard to determine if a given policy reduces VMT, and if so, by how much. More accurate predictions of VMT impacts would reduce the likelihood that resources are being wasted on ineffective policies and offer assurance to stakeholders that state policies are achieving their intended pollution and greenhouse gas goals. This project focuses on three areas of improvement: 1) A more accurate and complete measurement of VMT, particularly using phone and odometer data; 2) A more accurate causal understanding of how development or transportation projects with different characteristics affect VMT; 3) A more accurate and readily accessible way to forecast VMT impacts of projects in comparison to well-defined counterfactual scenarios. This new analysis will focus on the VMT impacts of land development projects and of transportation projects believed to mitigate or reduce VMT. Results will be translated into one or more demonstration tools showing how to better estimate project-level VMT or VMT-mitigation, drawing in part from consultations with practitioners who will constitute an advisory group for the project.

Do Existing Policies Still Hold? Quantifying Enduring Post-COVID Travel Patterns and Calibrating Policies

Status

In Progress

Project Timeline

January 1, 2026 - December 31, 2026

Principal Investigator

Project Team

David Bunch, Siddhartha Gulhare

Campus(es)

UC Davis

Project Summary

The pandemic has caused lasting changes in when, where, and why people travel, affecting transportation policies built on pre-pandemic habits. This proposal explores the scale and structure of travel shifts after the pandemic. It evaluates whether California’s Sustainable Communities Strategies (SCS), targeted programs like Green Means Go, remain effective, and if SB 743 aligns with new travel behaviors. Utilizing LEHD LODES and Replica data, the project team analyzes origin-destination patterns by time-of-day, trip purpose, and residential choices across industries from 2019 to 2024. The research uses term clusters (representing complete communities), where residents can live, work, and access daily needs within the same area. First, the team analyzes intra- and inter-cluster travel changes to determine whether travel has become localized or dispersed. Second, researchers examine whether the self-sufficient cluster model, where people can live, work, and recreate within the same area, is consistent across industries and income groups. Finally, the team evaluates if hybrid work patterns have changed job-housing balance and impacted the resilience of clusters targeted for infill and VMT reduction. This study offers timely empirical insights to assist state policymakers (SACOG, SCAG) in revisiting policy assumptions, updating SB 375 implementation strategies, and identifying where local plans may need recalibration to meet California’s goals.

State Preemption and Parking Requirements

Status

Complete

Project Timeline

August 1, 2023 - December 31, 2025

Principal Investigator

Campus(es)

UCLA

Project Summary

We consider how cities are responding to California’s legislation that preempts them from requiring parking close to transit. To what extent are cities sticking to the letter of the law? Which cities are going further and taking the opportunity to go beyond the scope of the state requirements? Or are some cities attempting to evade the spirit of the law?

Do Parking Requirements Reflect Anti-Muslim Bias?

Status

Complete

Project Timeline

September 25, 2023 - June 30, 2027

Principal Investigator

Project Team

Adam Millard-Ball, Huzaifa Shahbaz

Campus(es)

UC Santa Cruz, UCLA

Project Summary

The negative impacts of minimum parking requirements are well established. More parking leads people to buy more cars and drive them more, which contributes to air pollution, climate change, and road injuries and deaths. Parking requirements also constrain densities and make it difficult to adaptively reuse historic buildings. More recent studies have highlighted the equity consequences of minimum parking requirements, such as increasing rents and constraining the supply of affordable housing. This project addresses an equity concern regarding the potential disparate impact of parking requirements on minority religious communities in California, particularly Muslim communities. Previous research has indicated that Muslim mosques often face demands for additional parking beyond mandated minimums, exceeding the variances typically granted to Christian churches. In collaboration with the community-based organization Council on American-Muslim Relations the project team will investigate and analyze the disproportionate financial burdens placed on mosques in contrast to churches during parking discussions that may seem innocuous. To do this, the researchers will study a sample of 30 to 40 new mosques constructed since 2010 and create a paired dataset that matches them with churches built around the same time in similar locations. Using this paired dataset, they will conduct qualitative interviews with city officials, as well as Muslim and Christian religious leaders, to examine how parking requirements influenced the planning approval processes and to identify potential instances of anti-Muslim bias facilitated by these requirements.