Bridges deice themselves as part of pilot project
The Pennsylvania Department of Transportation is experimenting with bridges that clear themselves of snow and ice. Under a pilot program that is the first of its kind in the United States, three western Pennsylvania bridges have been outfitted with technology that senses when to apply de-icing material – and then applies it.
The three bridges – one near Pittsburgh in Allegheny County, one in Warren in Warren County and one on U.S. Route 30 in Westmoreland County – are connected to a Road Weather Information System that monitors wind speed and direction, as well as air temperature, humidity, dewpoint and general weather conditions. Probes in the bridge decks read surface temperature, do chemical analyses of the material on the bridges and provide daily traffic counts.
Computers relay information to the county offices. When specific conditions are met, nozzles imbedded in the bridges’ centerlines spray magnesium chloride on the road at a height of 7 inches. (The Swiss manufacturer, Boschung, designed the technology being used by PennDot.)
“We started the program out west because we have a better chance of freezing precipitation out there,” says Penn-Dot spokesperson Steve Chizmar. “The three bridges were chosen partly because they have a history of freezing quickly.” The idea for the project came from the PennDot rank and file. “A group of us got together to work on an RFP for weather information systems,” says PennDot District Manager Bill Monstrola. “Once we got that developed, part of the group started talking about going further.”
Performance data is limited. The program is in its first year, and PennDot is making adjustments. “We’re tweaking the number of gallons of magnesium chloride, stuff like that,” Chizmar says. Additionally, Monstrola points out that all the computer systems are not yet in place.
However, the weather has cooperated fully with the effort. “We were fortunate to get 15 or 20 snow conditions early,” Monstrola says. “That gave us lots of opportunity to evaluate the system.”
The pilot program cost PennDot $552,000, but Chizmar argues that it was money well spent. “The bridges are not only going to be safer, but the system allows operators to concentrate on other areas of their jobs,” he says.