High-tech sensor halts ice on N.H.-Vt. bridge

Drivers heading into New Hampshire from Vermont on Interstate 89 this winter will have some high-tech help to keep them on the road. Crews have finished installing a sophisticated system that uses sensors to detect when ice is about to form on the I-89 bridge over the Connecticut River, then sprays the road surface with anti-icing fluid to prevent it from getting slick.

Denis Boisvert of New Hampshire’s Transportation Department says that the fluid is not a de-icer, which melts ice that already has formed. It is an anti-icing chemical, which prevents it from forming in the first place. “It’s a pre-emptive strike,” Boisvert said.

Sensors on the bridge deck and nearby track the temperature and moisture levels in the air and on the deck to predict when freezing is about to occur, and trigger a system of sprinklers embedded along the roadway’s centerline. Each time the rain, snow or moisture on the surface approaches the freezing point, it will get another hit of potassium acetate. It’s especially helpful on bridges over rivers, such as the I-89 bridge, where rising mist or moisture might cause black ice when nearby roads are clear and dry.

The system is made by Boschung America of Newcastle, Pa., which has 40 systems on roads and bridges in 15 states and one Canadian province. The I-89 test is the first in New England.

Boschung has 10 systems running in Pennsylvania. “We did see a marked decrease in the number of weather-related crashes on those bridges,” PennDOT spokesman Steve Chizmar told The Associated Press.