The Infrastructure Effect: Building better bridges and buses

This post is part of a series exploring the impacts of federal investments in home electrification, transportation, supply chains, and climate resilience.

Federal investments in repairing bridges and electrifying buses in the U.S. benefit low-income and disadvantaged communities, Carnegie Mellon University research shows.

Families in these communities experience more pollution and worse infrastructure than their wealthier counterparts - inequities likely to increase if federal funding is at risk.

Carnegie Mellon University research found that the electrification of the U.S. transit bus fleet could reduce air pollution, and slash transit bus greenhouse gas emissions by 33% to 65% within the next 14 years.

The transportation sector is the largest emitter of greenhouse gasses in the U.S. Increasing the use of public transportation is a simple way to reduce traffic, air pollution and greenhouse gas emissions. 

Traditional buses operate in cities where air pollutants and noise disproportionately affect disadvantaged communities. Electrifying the bus fleet will improve the quality of life in cities and those communities.

The CMU research focused on the approximately 70,000 transit buses in the U.S. About 22% of the fleet was already eligible for replacement in 2021. The research found that electric bus technology could reach levelized cost parity with diesel buses when electric bus capital costs fall below about $670,000 per bus.

The Bipartisan Infrastructure Law (BIL) included $5.6 billion in grants to reduce emissions from public transit by buying buses with low or no tailpipe emissions through the Federal Transit Administration’s Low or No Emission Grant Program. The BIL also dedicated $5 billion to the Environmental Protection Agency’s Clean School Bus program to replace school buses with zero-emission and clean school buses.

A separate CMU study focused on the equity of bridge management. Researchers found that bridges located in low-income neighborhoods and disadvantaged communities are more likely to be in poor condition. It also revealed that historically Black communities were associated with a greater likelihood of having bridges in worse condition — even when accounting for household income.

Communities that rely on bridges for efficient and safe travel suffer when bridges are suddenly closed due to failures. This study suggests that disadvantaged and Black communities are more likely to face deteriorating and unsafe bridges.

The researchers compared the performance of more than 580,000 bridges inventoried over a 31-year period by the socioeconomic disadvantage, race, and ethnicity of the community next to each bridge.

The BIL appropriated $27.5 billion for the Bridge Replacement, Rehabilitation, Preservation, Protection, and Construction Program (also known as the Bridge Formula Program) for fiscal years 2022 through 2026. 

Social metrics used to prioritize bridge investments are typically limited to the impacts on highway users such as average daily traffic and detour length in the event the bridge is closed. This study suggests that the demography, resources, and resilience of the neighboring communities should inform that decision making.

More broadly, CMU research shows that targeted federal investments in bridges and buses can improve safety and quality of life for residents of disadvantaged communities.