"Black carbon and NO2 are harmful to everyone's health," Bickford says. "But because more people live near roads than railroad tracks, more people would benefit from the shifts in these pollutants."
As much as 16 percent less black carbon soot would linger near roads with heavy shipping traffic, according to Bickford's model, while the increase around rail corridors would be as high as 20 percent. Nitrogen dioxide would plummet by as much as 30 percent near roads, but rise by as much as 20 percent near railroad tracks.
Holloway's research group is already working on further modeling to explore connected changes in the number of asthma and heart disease cases.
The effects of greater rail use would be particularly noticeable in the middle of the country, according to Bickford.
"We're sort of a freight crossroads in the Midwest," says Bickford, whose work was funded by the National Center for Freight & Infrastructure Research & Education at UWMadison. "International shipping comes into the country on the coasts and then passes through our backyard on the way to its destination."
The study limited hypothetical changes in shipping to trips of more than 400 miles to ensure a cost savings for shippers, and to cargo such as automobiles and non-perishable food that could handle the slower trip in railcars. The 500 million tons Bickford selected for travel by rail represent about 5 percent of U.S. truck freight by weight.
"These aren't pie-in-the-sky figures," Holloway says. "They are reasonable and achievable."
And they come with non-pollution benefits, like reduced traffic congestion, wear on roads and demand for diesel fuel.
"Truck freight travels on publically-funded roads, rail traffic on privately-built tracks," Bickford says. "But these benefits could be an impetus for public investment in rail infrastructure."
|Contact: Erica Bickford|
University of Wisconsin-Madison