policy brief

Evaluating Equity in Transportation and Hazard Preparedness Plans: A Multi-Level Governance Approach

Abstract

Environmental justice (EJ) principles are essential for addressing inequities in transportation and hazard preparedness; however, they are often applied in a fragmented manner. Historically, urban planning in the United States has created racial and economic divisions, particularly through policies like redlining and freeway construction that displaced communities of color. These practices have systematically and disproportionately exposed marginalized groups to environmental harms. The EJ movement has advocated for addressing these disparities through equity-focused policies. However, the integration of EJ principles into plans remains incomplete, with prior studies focusing on individual plans or jurisdictions, failing to consider broader governance systems and the need for equity to bridge multiple plan types. These challenges are compounded by the shift from centralized to decentralized governance, creating a fragmented landscape where different levels of government and departments operate with distinct priorities. Multi-level governance (MLG) creates both opportunities and challenges for equity-centered planning. While it enables state funding, regional planning, and local implementation to align, fragmented jurisdictions often leave transportation, hazard, and climate plans in silos. Intentional coordination is needed to embed EJ principles across all levels of planning. This analysis focuses on Los Angeles due to its overlapping jurisdictions, large transit system, and history of environmental injustice making it a critical test case for how MLG can both enable and constrain equity-centered planning. This policy brief is based on our evaluation of 16 climate action, racial equity, transportation, and hazard preparedness plans in Greater Los Angeles, which was systematically scored based on three existing EJ pillars: Recognition Justice, Procedural Justice, and Distributive Justice

policy brief

Truck Parking and Idling is Having an Impact on Disadvantaged Communities in California

Abstract

Under California Assembly Bill 617 (Garcia, 2017), local and state agencies are working to reduce air pollution exposure in low income communities. These communities—often referred to as AB 617 communities—are disproportionately impacted by air pollution due to their proximity to transportation corridors, industrial installations, and logistics centers. A research team at the University of California, Davis investigated the impact of truck parking related activities on air quality in California’s AB 617 communities in Kern County, including truck idling, time spent searching for parking, and parking locations in communities. Searching for parking involves trucks driving extra miles to find available parking spaces, which leads to additional fuel consumption and increased emissions of pollutants such as nitrogen oxides (NOx) and particulate matter (PM 2.5 and PM 10). Once parked, prolonged or illegal parking can exacerbate congestion, noise, and localized pollution. These combined activities heighten exposure to harmful emissions in EJ communities, potentially leading to health issues (e.g., asthma and cardiovascular diseases). A comprehensive policy framework addressing truck parking facilities, management, and air pollution control is crucial for improving air quality and living conditions in AB 617 communities. There are a number of initiatives that could contribute to improving the conditions on these communities.

preprint journal article

Determinants of Mode Choice and Forgoing Travel for Mobility-of-Care Trips by Caregivers in California

Abstract

Caregivers, especially those living in rural areas, often face unique challenges due to the responsibility of managing the mobility needs of the people in their care. While most transportation research focuses on individual travelers, mobility-of-care trips remain underexplored, despite their importance to public health. This study aims to assess the determinants of mode choice and trip-making behaviors among caregivers in California, focusing on mobility-of-care trips both for healthcare and social recreation. Collaborating with the nonprofit organization Ohana Center, this Community Based Participatory Research applies a mixed methods approach. First, using stated preference survey data from 349 caregivers (4188 observations) in California, collected in May 2025, we estimate an integrated choice and latent variable (ICLV) model to examine determinants of mode choice and trip-skipping behavior. Then, we conduct a series of three workshops with community leaders with caregiving expertise in semirural Antelope Valley to gain deeper insights into place-based transportation barriers and potential solutions. Our findings reveal that travel cost, travel time, and wait time significantly affect decision-making across all modes, while walk time, cleanliness, and ADA accessibility exhibit significant mode-specific effects. Caregivers who are women or nonbinary or belong to households that earn less than $15k in gross annual income are more likely to forgo mobility-of-care trips. Social recreation trips are more likely to be skipped than healthcare trips. Caregivers under the age of 35 and those who do not have a disability exhibit relatively higher wellbeing (measured as a 5-item latent variable), and those with higher wellbeing are less likely to forgo mobility-of-care trips. Based on these findings, this study offers recommendations for community-based transportation solutions tailored to the specific needs of caregivers and their recipients.

policy brief

New Innovative Last-Mile Delivery Strategies Have Environmental and Equity Benefits, But There Can be Trade-Offs

Abstract

The advent of e-commerce has changed consumer behavior and brought about a growing last-mile delivery system. These deliveries provide consumers with access to goods and services that would otherwise require personal trips to brick-and-mortar locations or not be available. To improve the efficiency of last-mile delivery and mitigate potential effects on traffic, communities, and the environment, e-retailers are trying out a diverse set of distribution strategies. These include: (1) using light-duty vehicles such as electric vans and cargo bikes in conjunction with micro-hubs, consolidation centers, and staging areas to reduce heavy traffic and operational costs; (2) establishing collection points (e.g., parcel lockers) that allow customers to pick up their orders at convenient locations, without the need for additional delivery vehicle travel; (3) engaging independent drivers who can provide flexible and cost-effective delivery; (4) deploying autonomous delivery robots and unmanned aerial vehicles; and (5) replacing conventional fuel vehicle fleets with zero- or near-zero emissions vehicles. A team at the University of California, Davis explored the economic viability, environmental efficiency, and social equity impacts of these strategies with state of the art modeling techniques.

policy brief

Test Publication for Automations

presentation

Transit, Belabored: Issues and Futures for California’s Frontline Transit Workforce

website

From "Across the Tracks" to "Across the Freeway": A History of the Racialization and Exclusion behind the I-10 Freeway in Colton

Publication Date

May 30, 2025

Author(s)

Paul Ong, Chhandara Pech, Jacob Wasserman, Andres F Ramirez, Anastasia Loukaitou-Sideris, Leila Ullmann, Megan Riley

Abstract

Travel 62 miles east of Los Angeles and you will find an epicenter of global mobility. Colton, a small 16-square-mile city in San Bernardino County, has been a principal rail and logistics hub since its establishment in the late 19th century. More than 110 cargo trains pass through the city daily, and it sits amidst the many warehouses of the Inland Empire region that store imports before their distribution locally and nationwide. But for Colton’s communities of color, especially its Latino residents, these transportation systems have long been a double-edged sword — offering employment opportunities while also enforcing stark racial and spatial divides. Railroad tracks historically split the city in two: white, affluent North Colton and working-class, Latino South Colton. In the 1940s, when state officials began planning the San Bernardino Freeway/Interstate 10 route, the proposed alignment threatened to deepen these divisions and further marginalize South Colton. This storymap looks into the nearly decade of heated debate that ultimately led to a route that minimized direct displacement and racial impact — a rare outcome in freeway planning of the era, driven largely by cost considerations.

website

Freeway Revolts and Racially Exclusive Participatory Planning: A History of Organized Opposition to Freeway Construction in Pacoima

Publication Date

May 8, 2025

Author(s)

Anastasia Loukaitou-Sideris, Susan Handy, Paul Ong, Jesus M. Barajas, Jacob Wasserman, Chhandara Pech, Juan Carlos Garcia Sanchez, Andres F Ramirez, Aakansha Jain, Emmanuel Proussaloglou, Andrea Nguyen, Katherine Turner, Abigail Fitzgibbon, Francois Kaeppelin, Felipe Ramirez, Marc Arenas

Abstract

Located in northeast Los Angeles, Pacoima is one of the oldest neighborhoods in the San Fernando Valley. Today, it is also one of the most polluted. Within the neighborhood’s 4.3 square miles, Pacoima contains three freeways, a railroad line, a small airport, and more than 300 industrial facilities. Before the construction of the freeways beginning in the 1960s, however, the neighborhood looked very different. Once known as America’s “first Black suburb,” Pacoima had a rich history of activism; however, archival records of the time offer little to no evidence of pushback from Black residents to the State Division of Highways (the precursor to Caltrans), as the Simi Freeway/State Route 118 bulldozed through their community in the 1960s. This storymap looks into neighboring opposition that led to the chosen route cutting through Pacoima’s vibrant and diverse community.

preprint journal article

MobilityGPT: Enhanced Human Mobility Modeling with a GPT model

Abstract

Generative models have shown promising results in capturing human mobility characteristics and generating synthetic trajectories. However, it remains challenging to ensure that the generated geospatial mobility data is semantically realistic, including consistent location sequences, and reflects real-world characteristics, such as constraining on geospatial limits. This project reformats human mobility modeling as an autoregressive generation task to address these issues, leveraging the Generative Pre-trained Transformer (GPT) architecture. To ensure its controllable generation to alleviate the above challenges, the study proposes a geospatially-aware generative model, MobilityGPT. A gravity-based sampling method is proposed to train a transformer for semantic sequence similarity. The training process would be constrained via a road connectivity matrix that provides the connectivity of sequences in trajectory generation, thereby keeping generated trajectories in geospatial limits. Lastly, The study proposed to construct a preference dataset for fine-tuning MobilityGPT via Reinforcement Learning from Trajectory Feedback (RLTF) mechanism, which minimizes the travel distance between training and the synthetically generated trajectories. Experiments on real-world datasets demonstrate MobilityGPT’s superior performance over state-of-the-art methods in generating high-quality mobility trajectories that are closest to real data in terms of origin-destination similarity, trip length, travel radius, link, and gravity distributions.

policy brief

Examining Both Trip Level Mode Replacements and Daily Activity Patterns of Users is Required to Understand the Sustainability Potential of Micromobility

Abstract

Micromobility options such as electric bike-share and scooter-share services are a fundamental part of the existing shared mobility landscape. Research has shown that micromobility use can reduce car dependence. This is accomplished through trip-level mode replacement and adjustments in mode-use configurations in daily travel. Understanding the full potential of micromobility services as a car replacement can help cities better plan for the services to meet environmental sustainability goals. Researchers at the University of California, Davis collected GPS-based travel diary data from individual micromobility users from 48 cities in the US and examined their travel behavior and micromobility use patterns. They found that micromobility services can displace car use. To achieve environmental sustainability goals, cities must pursue options that will deliver benefits, such as micromobility services. This policy brief summarizes the findings from that research and provides policy implications.