The study, "The Public Health Costs of Traffic Congestion: A Health Risk Assessment," was published in the scientific journal Environmental Health. It is the first to attempt to quantify the public-health implications of growing traffic congestion in America, according to a statement issued by the Transportation Construction Coalition, which supported the study through a grant. TCC includes 29 national associations and labor unions with an interest in federal transportation policy.
"Our estimates of the total public-health costs of traffic congestion in the U.S. are likely conservative," according to the study. Authors point out their research considers "only the impacts in 83 urban areas and only the cost of related mortality and not the costs that could be associated with related morbidity, healthcare, insurance, accidents, and other factors."
The Harvard Center for Risk Analysis is a research institute within the Harvard School of Public Health. Researchers projected the estimated growth of traffic congestion -- and resulting vehicle emissions -- from the baseline year 2000 through 2030 if no additional transportation infrastructure capacity is provided to accommodate projected population growth. They focused on motor-vehicle emissions, using several models "to predict how much of what people are breathing in each urban area is attributable to emissions from traffic congestion." Previous health studies have shown that vehicle emissions contribute up to one-third of particulate matter in metropolitan regions.
Potential strategies to reduce traffic congestion range include better traffic management through congestion pricing, traffic-light synchronization, more efficient response to traffic incidents, and adding new highway and mass-transit capacity, according to TCC. (The American Association of State Highway and Transportation Officials released a series of three reports last year, "Transportation Reboot," that outlined recommendations for unlocking gridlock, unlocking freight, and and connecting rural and urban America. Those reports are available at expandingcapacity.transportation.org.)
"More refined models of traffic dynamics specific to each urban area linked to the public health models developed in the study could be used to explore the impacts of proposed strategies," TCC asserts.
The study found the number of additional premature deaths and public-health costs due to traffic congestion have been declining over the past 10 years and will continue to decline until about 2030, when they would again begin to rise. This can be attributed to a cleaner fleet of motor vehicles in America as older, more polluting vehicles are replaced with today's low-emission vehicles.
Harvard's 10-page report on transportation and public health is available at bit.ly/PHCTC.