research report

Mitigating Exposure and Climate Change Impacts from Transportation Projects: Environmental Justice-Centered Decision-Support Framework and Tool

Publication Date

October 25, 2023

Associated Project

Author(s)

Arpad Horvath, Fiona Greer, Jasenka Rakas, Joshua Apte

Areas of Expertise

Safety, Public Health, & Mobility Justice

View research report

Abstract

California must operate and maintain an effective and efficient transportation infrastructure while ensuring that the health of communities and the planet are not compromised. By assessing transportation projects using a life-cycle perspective, all relevant emission sources and activities from the construction, operation, maintenance, and end-of-life phases can be analyzed and mitigated. This report presents a framework to assess the life-cycle of human health and climate change impacts from six types of transportation projects: (1) Roadways; (2) Marine ports; (3) Logistical distribution centers; (4) Railyards; (5) Bridges and overpasses; and (6) Airports. The framework was applied using an integrated model to assess fine particulate matter (PM2.5) and greenhouse gas (GHG) emissions, noise impacts, and monetized damages (Value of Statistical Life, Social Cost of Carbon) from two case studies: routine resurfacing and vehicle operations on road segments within the San Francisco Bay Area using 2019 data, and annual marine, cargo, rail, trucking, and infrastructure maintenance operations at the Port of Oakland in 2020. The results suggest that emission sources in a project’s supply chain and construction (material production and deliveries, construction activities, fuel refining) can significantly contribute to the full scope of impacts from transportation systems. Equitable mitigation policies (e.g., electrification, pollution control technologies) need to be tailored to address the sources that impact communities the most.

Related Publications

policy brief

Equity Assessment of Transportation Should Incorporate Materials,Supply Chains, and Targeted Mitigation Policies

published journal article

Pavement resurfacing and supply chains are significant contributors to PM2.5 exposure from road transportation: evidence from the San Francisco Bay Area

published journal article

Pavement resurfacing and supply chains are significant contributors to PM2.5 exposure from road transportation: evidence from the San Francisco Bay Area

Publication Date

November 28, 2022

Associated Project

Mitigating Exposure and Climate Change Impacts from Transportation Projects: Environmental Justice-Centered Decision-Support Framework and Tool

Areas of Expertise

Safety, Public Health, & Mobility Justice

View published journal article

Abstract

There are hundreds of millions of kilometers of paved roads and many people live in proximity. Pollution from road transportation is a well-documented problem potentially leading to chronic health impacts. However, research on the raw material production, construction, operation, maintenance, and end-of-life phases of paved roads, and corresponding supply chains, is generally limited to energy consumption and greenhouse gas emissions. No previous research efforts on the life-cycle stages of pavements and road operation connect pollutant emission inventories to the intake of inhaled pollutants and resulting damages to exposed populations. We have developed a first-of-its-kind model quantifying human exposure to fine particulate matter (PM2.5) due to emissions from routine pavement resurfacing and vehicle operation. We utilize the Intervention Model Pollution Source-Receptor Matrix to calculate marginal changes in ground-level PM2.5 concentrations and resulting exposure intake from a spatially resolved primary and secondary PM2.5 emission precursors inventory. Under a scenario of annual road-resurfacing practices within the San Francisco Bay Area in California (population: 7.5 million), resurfacing activities, material production and delivery (i.e. cement, concrete, aggregate, asphalt, bitumen), and fuel (i.e. gasoline, diesel) supply chains contribute almost 65% to the annual PM2.5 intake from all the sources included in the study domain (the remaining 35% being due to on-road tailpipe emissions). Exposure damages range from $170 to $190 million (2019 USD). Complete electrification of on-road mobile sources would reduce annual intake by 64%, but a sizable portion would remain from material supply chains, construction activities, and brake and tire wear. Future mitigation policies should be enacted equitably. Results show that people of color experience higher-than-average PM2.5 exposure disparities from the emission sources included in the study, particularly from material production.

Related Publications

policy brief

Equity Assessment of Transportation Should Incorporate Materials,Supply Chains, and Targeted Mitigation Policies

research report

Mitigating Exposure and Climate Change Impacts from Transportation Projects: Environmental Justice-Centered Decision-Support Framework and Tool

policy brief

Could Transportation Network Companies help Improve Rail Commuting?

Publication Date

March 21, 2024

Associated Project

Coordinating Transit and Transportation Network Company Use in Support of Equitable Mobility and Livable Communities

Author(s)

Michael Cassidy, Wesley Darling

Areas of Expertise

Public Transit, Shared Mobility, & Active Transportation Safety, Public Health, & Mobility Justice

View policy brief

Abstract

Commuter rail is known to have a “first- and last-mile” problem (i.e., a lack of options for getting commuters to and from a rail station). The first- and last-mile dilemma creates inequalities in access. For example, high-income commuters drive to work (forgoing transit altogether), middle-income commuters drive to a rail station and pay to park, and low-income commuters rely on feeder buses or walking to reach a rail station. Transportation network companies (TNCs), like Uber and Lyft, are a viable option for connecting travelers to rail stations, especially for those who don’t own a car, however, their high fares make them attractive only to higher-income travelers. To close this equity gap, subsidies could be provided for TNC rides that connect travelers to commuter rail. To explore this concept further, we developed idealized (but physically realistic and rational) models to describe communities in the San Francisco Bay Area, and simulated the effects of various subsidization policies (i.e., providing subsidies for TNC rides to and from rail stations, increasing rail stations parking fees) using real-world data representative of Bay Area commuter populations.

Related Publications

research report

Subsidizing Transportation Network Companies to Support Commutes by Rail

research report

Subsidizing Transportation Network Companies to Support Commutes by Rail

Publication Date

March 21, 2024

Associated Project

Coordinating Transit and Transportation Network Company Use in Support of Equitable Mobility and Livable Communities

Author(s)

Wesley Darling, Michael Cassidy

Areas of Expertise

Public Transit, Shared Mobility, & Active Transportation Safety, Public Health, & Mobility Justice

View research report

Abstract

The research team explores how rail transit’s first- and last-mile issues might be addressed by partnering with transportation network companies (TNCs) like Uber and Lyft. The goal is to lure high-income commuters to shift from cars to TNCs and rail. The team also explores how rail and TNC partnerships can improve travel for low-income commuters who currently rely on low-frequency bus services. The researchers parametrically test subsidizing TNC fares for feeder services in the San Francisco Bay Area in an idealized fashion. Inputs such as the residents’ value of time and vehicle ownership were taken from various local data sources. The communities that were selected for the study are served to different degrees by the BART rail system. The research includes that the optimal policy must be tailored to the characteristics of the community it serves. In dense, walkable communities with strong bus service near rail stations, TNC subsidies should be targeted to less accessible neighborhoods and low-income commuters to not compete with bus transit and active modes like walking. For lower-density communities with limited dedicated bus feeder service, TNC subsidization can be applied more broadly, although disincentives, like increasing rail parking fees, must be considered carefully because they can induce commuters to drive directly to work instead. The research paper concludes with a discussion of how subsidies might be covered by reallocating existing resources in different ways.

Related Publications

policy brief

Could Transportation Network Companies help Improve Rail Commuting?

policy brief

Travel Varies Greatly Between Voluntary Versus Involuntary Carless Households in California

Publication Date

May 1, 2020

Associated Project

An Analysis of Travel Characteristics of Carless Households in California

Author(s)

Jean-Daniel Saphores

Areas of Expertise

Travel Behavior, Land Use, & the Built Environment

View policy brief

Abstract

In spite of the critical importance of mobility for quality of life and economic well-being, the travel behavior of households without motor vehicles has received insufficient attention even though “carlessness” may bethe most vivid expression of mobility disadvantage in our car-centric society. Approximately 10.6 million (9 %) of U.S. households do not own a motor vehicle (car, pickup, van, SUV, or motorbike), including over one million in California. These “carless” households form two groups: (1) involuntarily carless households who are forced to live without cars, and (2) voluntarily carless households who chose to do so. Since one of the strategic goals of federal transportation policy is “to increase transportation choices and access to transportation services for all” it is essential to understand the travel behavior of households who are unable to own a motor vehicle. Indeed, many involuntarily carless households are experiencing economic hardship, disabilities, racial and age discrimination, or cultural barriers. Understanding the travel pattern of voluntarily carless households is also necessary to formulate policies aimed at decreasing vehicle use. Reducing personal vehicle use would help relieve congestion, decrease road accidents, improve air quality, cut emissions of greenhouse gases, and improve the health of people who switch to more active modes, such as walking and biking.

Related Publications

published journal article

How do they get by without cars? An analysis of travel characteristics of carless households in California

research report

An Analysis of Travel Characteristics of Carless Households in California

policy brief

A Review of Reduced and Free Transit Fare Programs in California

Publication Date

May 1, 2020

Associated Project

A Review of Reduced and Free Transit Fare Programs in California

Author(s)

Jean-Daniel Saphores

Areas of Expertise

Public Transit, Shared Mobility, & Active Transportation

View policy brief

Abstract

Free or reduced-fare transit passes have the potential to increase transit ridership, enhance the mobility of underserved groups (e.g., low-income, seniors, and youth), and reduce the environmental footprint of transportation. Under the right conditions, these programs can also help reduce traffic congestion and motor vehicle use. Transit agencies in different parts of the world have been experimenting with free or reduced-fare transit for decades, yet there are still substantial concerns about the impacts of free or reduced-fare transit on ridership as well as on the fiscal health of transit agencies. Some of these concerns linger partly because rigorous academic studies on free and reduced-fare transit passes are still rare.

Related Publications

research report

A Review of Reduced and Free Transit Fare Programs in California

research report

Financing the Future: Examining the Fiscal Landscape of California Public Transit in the Wake of the Pandemic

Publication Date

April 10, 2023

Associated Project

Financing the Future: Examining the Fiscal Landscape of California Public Transit in the Wake of the Pandemic

Author(s)

Brian D. Taylor, Fariba Siddiq, Hannah King, Hao Ding, Jacob Wasserman, John Gahbauer

Areas of Expertise

Public Transit, Shared Mobility, & Active Transportation Transportation Economics, Funding, & Finance

View research report

Abstract

California and its regional and local governments have invested heavily in public transit over the past half-century to provide an alternative to driving, ease traffic congestion, reduce emissions, slow climate change, steer new development, and provide mobility for those without. As a result, bus service has improved and expanded, and many parts of the state’s metropolitan areas are now served by rail transit. Yet today, many of the state’s transit systems are struggling operationally and financially. Ridership began eroding in the half-decade leading up to 2020 and plummeted at the start of the COVID-19 pandemic. Three federal pandemic relief bills provided a critical lifeline to keep struggling transit systems afloat early on, but these funds are running out. Meanwhile, operating costs have risen, ridership and fare revenues have only partially returned, and some transit systems face “fiscal cliffs,” where they will need substantial new infusions of funding, substantial cuts in costs and service, or some combination of the two. Against this backdrop, this report examines the current state of California transit finance: why ridership and fare revenues are down and their prospects for recovery; what lessons the successful federal relief bills provide; why commuter-oriented systems are struggling financially much more than those that primarily service transit-reliant riders; and what the financial managers at transit systems have done to cope with this turbulent time and how they see their future financial prospects.

Related Publications

published journal article

Terra Incognita: California Transit Agency Perspectives on Demand, Service, and Finance in the Age of COVID-19

policy brief

Public Transit’s Post-pandemic Fiscal Challenges

published journal article

Transit’s Financial Prognosis: Findings from a Survey of U.S. Transit Systems during the COVID-19 Pandemic

research report

Zero-Emission Bus Implementation Guidebook for California Transit Fleets

Publication Date

April 1, 2023

Associated Project

Zero-Emission Bus Implementation Guidebook for California Transit Fleets

Author(s)

Emily Rogers, Timothy Lipman

Areas of Expertise

Public Transit, Shared Mobility, & Active Transportation Zero-Emission Vehicles & Low-Carbon Fuels

View research report

Abstract

Transit bus operations in California are experiencing new challenges due to economic conditions and the ongoing global pandemic. A confluence of factors has created a focus on this critical public-needs-serving industry, due to state and local efforts to reduce emissions of pollutants and climate-changing gases. Transit bus operations in California provide essential and additional useful services that offer critical mobility to needy populations (elderly and handicapped) as well as many other groups for whom transit buses provide the most economical, convenient, and low-emission options. To address the role of transit bus operations in meeting California’s aggressive greenhouse gas (GHG) and emissions, the California Air Resources Board (ARB) has implemented an ambitious Innovative Clean Transit (ICT) regulation that requires all public transit agencies to gradually transition to a 100 percent zero-emission bus (ZEB) fleet.1 Beginning in 2029, 100% of new purchases by transit agencies must be ZEBs, with a goal for a full transition by 2040. Prior to that 25% of purchases of new buses must be ZEBs in 2023-2025 for large transit agencies, rising to 50% in 2026-2028. For smaller transit agencies, defined as those with less than 100 buses in annual maximum service, there is no requirement for 2023-2025 and the requirement for 2026-2028 is 25%, but the 100% ZEB purchase requirement starting in 2029 applies to all agencies.

policy brief

How Seven Cities Are Exploring Congestion Pricing Strategies

Publication Date

March 29, 2023

Associated Project

Lessons from Cities Considering Congestion Pricing

Author(s)

Jonathon Colner, Mollie Cohen D'Agostino

Areas of Expertise

Transportation Economics, Funding, & Finance

View policy brief

Abstract

Congestion pricing is a vehicle tolling system that imposes fees to drive within a congested area, typically a downtown district. Cities that already have congestion pricing policies in place have been studied extensively. Notable examples are Singapore, London, Stockholm, Milan, and Gothenburg. These cities have appreciated a range of benefits from congestion pricing, including reductions in peak traffic, vehicle miles traveled, and emissions, as well as increased revenues for transportation investments.