research report

Maximizing the Air Quality and Environmental Justice Benefits of Zero Emission Off-Road Vehicles and Equipment in California

Publication Date

October 29, 2025

Associated Project(s)

Maximizing the Air Quality and Public Health Benefits of Zero-Emission Off-Road Equipment in Disadvantaged Communities

Author(s)

Michael MacKinnon, Kai Wu, Scott Samuelsen

Areas of Expertise

Zero-Emission Vehicles & Low-Carbon Fuels

View research report

Abstract

Diesel fuel powered off-road vehicles and equipment used in agriculture, construction, mining, and industry have significant air quality and public health impacts due to high levels of pollutant emissions. Replacing these with zero emission powertrains represents a key strategy for reducing the harmful environmental impacts. However, the air quality impacts of zero emission off-road vehicles have not been assessed. Using the CMAQ model, we find that fully converting the off-road sector to zero emission equipment can decrease annual PM2.5 up to 0.9 μg/m3 and reduce daily maximum 8-hr average (MDA8) ozone as much as 6 ppb in Southern California. Statewide, these improvements yield benefits to public health potentially ranging up to $22.0 billion annually. The results further demonstrate the ability of zero emission off-road equipment to achieve health benefits within socially and economically disadvantaged communities.

Related Publications

policy brief

Switching to Zero Emission Off-Road Vehicles and Equipment Has Significant Air Quality and Environmental Justice Benefits in California

published journal article

State Preemption in Theory and Practice: The Case of Parking Requirements

Publication Date

October 17, 2025

Associated Project(s)

State Preemption and Parking Requirements

Author(s)

Amy Lee, Adam Millard-Ball, Michael Manville

Areas of Expertise

Travel Behavior, Land Use, & the Built Environment

View published journal article

Abstract

In U.S. law, states can override actions of local governments that contravene state interests. In practice, preemptions are often more ambiguous nudges, and local responses can vary by interpretation and interests. This paper explores one such case of state preemption: California’s 2022 law that limited local governments’ ability to require automobile parking. We find that the law’s complexity and ambiguity created intense debates about interpretations, in all jurisdictions, leading to heterogeneous implementation across cities. Local interests also motivated strategic responses to the law, which we present in a threefold taxonomy: cities interested in parking reform used it as a springboard; cities interested in parking reform but facing local resistance used it as a protective shield; recalcitrant cities treated it as an obstacle or subverted the law. Our analysis shows that preemption is not as clear cut as it seems, and what conditions help and hinder changes in actual outcomes.

policy brief

Switching to Zero Emission Off-Road Vehicles and Equipment Has Significant Air Quality and Environmental Justice Benefits in California

Publication Date

October 28, 2025

Associated Project(s)

Maximizing the Air Quality and Public Health Benefits of Zero-Emission Off-Road Equipment in Disadvantaged Communities

Author(s)

Michael MacKinnon, Kai Wu, Scott Samuelsen

Areas of Expertise

Zero-Emission Vehicles & Low-Carbon Fuels

View policy brief

Abstract

Off-road vehicles and equipment (e.g., forklifts, tractors, dirt bikes) are a major source of air pollution in California due to their heavy reliance on diesel engines, which emit high levels of nitrogen oxides (NOx), fine particulate matter (PM2.5), and other emissions. These pollutants cause a range of health impacts, including respiratory diseases like asthma, increased cancer risk, premature death, and other ailments, and disproportionately affect low-income communities located near highways, freight hubs, ports, and industrial areas. To address this issue, California has a range of policies and programs in place seeking a cleaner off-road sector beginning with Executive Order N-79-20, which sets a goal of 100 percent transition to zero emission (ZE) off-road vehicles and equipment by 2035 where feasible. Reflecting this, the California Air Resources Board (CARB) 2022 California Scoping Plan outlines ambitious ZE technology adoption, including hydrogen fuel cell and battery electric technologies. To better understand the implications of both current and future policies, this study quantifies 1) the benefits of off-road emission reductions from current policy and 2) potential additional benefits that can be achieved by increasing ZE adoption of off-road vehicles and equipment over and above the level considered feasible in the Scoping Plan up to and including a full transition to ZE.

Related Publications

research report

Maximizing the Air Quality and Environmental Justice Benefits of Zero Emission Off-Road Vehicles and Equipment in California

research report

Advancing procedural equity in environmental benefit programs: Insights from California’s electric vehicle purchase programs

Publication Date

October 1, 2025

Associated Project(s)

Assessing Procedural Equity in California’s Electric Vehicle Purchase Programs

Author(s)

Rachel Connolly, Gregory Pierce, Viviana Morales

Areas of Expertise

Zero-Emission Vehicles & Low-Carbon Fuels

View research report

Abstract

The California Air Resources Board (CARB) offers several benefit programs that support residents with the transition to electric vehicles. The Clean Vehicle Assistance Program (CVAP) provided grants and financing to help low-income households purchase or lease electric vehicles from 2018–2024. The Access Clean California (ACC) program streamlines access to clean transportation incentives through a network of community outreach partners. This study examines procedural equity in these two programs through interviews with CARB staff, program administrators, community partners, and program participants. The study concludes CVAP fell short in several ways, including insufficient community engagement and a lack of targeted outreach, funding instability resulting in frequent program closures, and challenges in successfully distributing low-interest loans, while the ACC program has not fully simplified incentive access. The study recommends improved transparency in program reporting, regular third-party equity evaluations, strategic development of a truly equitable financing program, and refined funding allocation and administration to enhance equity outcomes.

Related Publications

policy brief

Bridging the Procedural Equity Divide in California’s Electric Vehicle Incentive Programs

policy brief

Resilience Hubs are a Community Resilience Strategy That Should be Better Integrated Into Los Angeles’ Public Transit System

Publication Date

October 22, 2025

Associated Project(s)

Exploring Opportunities to Improve Transit Access to Community Resilience Centers for Safety and Evacuation Planning

Author(s)

Elisa Borowski, Jeannine Pearce

Areas of Expertise

Public Transit, Shared Mobility, & Active Transportation

View policy brief

Abstract

This research was motivated by the need to better understand how the hazard preparedness and resilience strategies of California’s public transportation system can be improved through integration with social and safety infrastructure. The study focuses on a specific type of social infrastructure called ‘Resilience Hubs’, which are community-operated and community-serving facilities that support residents in accessing resources and support during both everyday conditions and extreme events. Considering the potential of these hubs to enhance resilience and safety for historically marginalized individuals, public sector decision makers must understand the function and impact of Resilience Hubs and ensure access to them. To better understand the role of social infrastructure like Resilience Hubs in supporting safety and hazard preparedness, as well as its integration with public transit, the researchers collaborated with one of Los Angeles’ first Resilience Hubs as of 2021: the Boyle Heights Arts Conservatory (BHAC). In partnership with the BHAC and the local non- profit Climate Resolve, the researchers collected data through three listening sessions with a total of 26 residents of Boyle Heights, Los Angeles, with connections to the BHAC. The research sought to amplify how residents of Boyle Heights experience cascading urban vulnerabilities and resilience, both in terms of physical and social infrastructure, as well as the improvements they envision for public transit integration with social infrastructure to enhance the resilience of both systems.

Related Publications

research report

Reimagining Transportation as a Social Service to Build Resilience and Support Community Power

policy brief

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

preprint journal article

Beyond Infrastructure: Patterns of Environmental Justice and Multi-Level Governance in Greater Los Angeles Transportation and Hazard Planning

policy brief

Bridging the Procedural Equity Divide in California’s Electric Vehicle Incentive Programs

Publication Date

October 1, 2025

Associated Project(s)

Assessing Procedural Equity in California’s Electric Vehicle Purchase Programs

Author(s)

Rachel Connolly, Gregory Pierce, Viviana Morales

Areas of Expertise

Zero-Emission Vehicles & Low-Carbon Fuels

View policy brief

Abstract

As a leader in clean transportation initiatives, the California Air Resources Board (CARB) has long offered several benefit programs that support residents with the transition to electric vehicles, including the Clean Vehicle Assistance Program (CVAP) and Access Clean California (ACC). CVAP, which operated from 2018-2024, provided grants and loan financing to help low-income households purchase or lease electric vehicles. ACC, launched in 2018, uses an extensive statewide community outreach network of community-based organizations (CBOs) to connect eligible residents with a range of clean transportation and energy benefits. While there is substantial knowledge about the distributive equity outcomes of many of the state’s clean transportation programs, procedural equity—ensuring inclusivity in design, outreach, and other aspects of implementation—remains less explored. This study examined procedural equity in these two programs, selected for their innovative program designs and priorities beyond those of more long-standing, pure vehicle purchase credit or rebate approaches.

Related Publications

research report

Advancing procedural equity in environmental benefit programs: Insights from California’s electric vehicle purchase programs

published journal article

Hybrid Workers’ Activity Intensity: Post-Pandemic Comparison of Telework-Only and in-Person Workdays

Publication Date

August 29, 2025

Associated Project(s)

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

Author(s)

Patrick Loa, Yongsung Lee, Giovanni Circella

Areas of Expertise

Travel Behavior, Land Use, & the Built Environment

View published journal article

Abstract

The COVID-19 pandemic profoundly reshaped work patterns, with a sizable portion of workers becoming engaged in hybrid work (i.e., combining teleworking and in-person work). This study investigates whether hybrid workers, in the post-pandemic era, participate in out-of-home activities differently on their telework days than on their in-person workdays. Using data from 1,438 hybrid workers in California, US, collected during fall 2023, we estimate a multivariate ordered-response probit model with threshold shifters. Differences in participation across six out-of-home activities (shopping, errands, drop-off/pick-up, eating out, visiting friends and family, and exercise) between telework and in-person workdays are jointly modeled. Workers show greater overall activity participation on telework days, with considerable heterogeneity among individuals. On telework days, women and older workers tend to have lower participation in out-of-home activities. Flexible work schedules are associated with higher participation in social activities. Greater time savings (from not having to physically commute) lead to higher overall participation. The results underscore the importance of policies that support flexible work arrangements, considering their potential to positively affect lifestyle and productivity. Additionally, teleworking at non-home locations is linked to higher activity participation overall, suggesting potential trip-chaining or unique activity allocation strategies that warrant further investigation. The study contributes to the literature on post-pandemic teleworking and activity participation, and offers valuable insights into urban planning, transportation policy, and remote-work policies.

policy brief

Using a “Bathtub Model” to Analyze Travel Can Protect Privacy While Providing Valuable Insights

Publication Date

October 14, 2025

Associated Project(s)

Development of New Privacy-preserving Method for Traffic Data Collection and Analysis

Author(s)

Wenlong Jin, Joseph H. F. Lo

Areas of Expertise

other

View policy brief

Abstract

Transportation agencies increasingly rely on detailed trip data to analyze traffic patterns and plan infrastructure improvements. However, traditional data collection methods require extensive personal information about travelers’ origins, destinations, and routes, raising serious privacy concerns. Current “big data” approaches can track individual movements with alarming precision, often without explicit consent. As privacy regulations tighten and public concerns grow, transportation planners need alternative methods that balance analytical needs with privacy protection. To address this challenge, the research team evaluated the “bathtub model” as a privacy-preserving alternative to traditional traffic data collection methods. This simple, network-level approach treats all trips in a region as part of one system. Instead of tracking each person’s path, a bathtub model represents trips by how much distance they have left to travel. This allows for analyzation of network performance while protecting privacy.

white paper

Coordinated Operation of Shared Micro-mobility for a Sustainable City Transportation System

Publication Date

October 1, 2025

Associated Project(s)

Coordinated Operation of Shared Micro-Mobility to Support a Sustainable Transportation System

Author(s)

Shams Tanvir, Meagan Chan, Kanok Boriboonsomsin, Matthew Barth, Alyssa Labrador

Areas of Expertise

Public Transit, Shared Mobility, & Active Transportation

View white paper

Abstract

At present day, there are little to no policies around the use and implementation of micro-mobility in many cities. At the national level, there are no specific guidelines that outline how micro-mobility parameters should be implemented in a city. The National Transportation Board has left it up to
metropolitan districts to decide on how to gauge the decision to install micro-mobility systems in their cities. However, best practice guidelines have been identified by the National Association of City Transportation Officials (NACTO) and the U.S. Department of Transportation Federal Highway Administration (FHWA).

policy brief

The Missing Link in Automated Vehicle Safety: Projected Braking and Realistic Driving Behavior

Publication Date

October 14, 2025

Associated Project(s)

Examining the Safety and Efficiency Implications of Several Autonomous Car-following Models

Author(s)

Wenlong Jin

Areas of Expertise

Intelligent Transportation Systems, Emerging Technologies, & Big Data Safety, Public Health, & Mobility Justice

View policy brief

Abstract

As more automated vehicles (AVs) gradually appear on our roads, they must be able to safely interact with human drivers as well as existing infrastructure designed with human drivers in mind. Current car-following computer models—which determine how AVs adjust their speed and position relative to other vehicles—often struggle to replicate human driving patterns. This deficiency could lead to unpredictable AV behavior, potentially increasing crash risks, disrupting traffic flow, and creating problems at traffic lights and intersections designed for human drivers. If AVs brake much earlier or later than humans, drivers may be caught in ‘dilemma zones’ — unable to safely stop or proceed through the intersection. To address these challenges, the research team conducted a comprehensive analysis of existing car-following models and developed a novel multi-phase projection-based model that ensures safety while exhibiting human-like driving characteristics.

Related Publications

preprint journal article