The Interstate 94 bridge over the Red River is expected to be safer for drivers in 2006 when a $1.2 million automated de-icing system is operational.
The bridge between Moorhead and Fargo - labeled as a high-crash location by the North Dakota Department of Transportation - will be the third regional site to feature the system.
North Dakota installed a de-icing system on an Interstate 29 bridge at Buxton in December 2002. Minnesota installed one on a Highway 336 bridge east of Dilworth between U.S. Highway 10 and I-94 two years ago.
"De-icing systems are pretty new to North Dakota," said Troy Gilbertson, Fargo maintenance coordinator for the state Highway Department. "I'm lucky enough to have two of them."
The department, which is splitting the system's cost with the Minnesota Department of Transportation, began installing the I-94 bridge system in September. Gilbertson hopes to have it running by Jan. 1.
Bridges traditionally form ice faster than roadways because cold air passes above and below the elevated plane, Gilbertson said.
The de-icing system is designed to combat weather by spraying the bridge's surface with chemicals before ice forms. The technology uses sensors embedded on the bridge's deck and a small weather station to monitor air and pavement temperatures, humidity, visibility, wind speed and whether the bridge is wet or dry.
Another set of sensors cools or warms liquid to determine its freezing point.
Information collected from the sensors and weather station is routed to computers in separate pump houses on westbound and eastbound lanes of the bridge. The pump houses contain 2,000-gallon tanks of the anti-icing chemical and control pumps.
The computers rely on information from the weather station and sensors to determine the amount of chemical to spray.
Gilbertson said the chemical used to prevent freezing is environmentally safe.
Information from the computers will be sent to Gilbertson's office three miles away, where he can manually operate the sprayers if necessary.
Two snapshot cameras will be installed at opposite ends of the bridge. Images can be viewed at the NDDOT Web site - www.state.nd.us/dot.
Gilbertson said the images will be updated every five minutes and can help visitors gauge driving conditions.
Sensors and sprayers will begin near the Highway 75 bridge in Moorhead, about 800 feet before the 1,300-foot Red River bridge. Thirty 6-inch spray disks will be embedded into the eastbound lane and 42 in the westbound lane.
Gilbertson said preventing ice or black ice from forming is the reason the sprayers begin so far from the bridge.
Minnesota road maintenance crews are pleased with the de-icing system on Highway 336, said MnDOT's Shiloh Wahl, the project's engineer.
Although it's too early to determine how well the $420,000 Highway 336 system prevents accidents, Wahl said the department is seeing positive results.
Wahl said the cost-benefit of the system will become evident with fewer accidents and lower ice removal and bridge maintenance costs. The state has an annual maintenance agreement with the installer of the system.
"I think you'll be seeing more of these systems" in the future, Wahl said. "The longer the system is in place, the more data we can collect on how the system is working and if they truly are preventing less accidents."
The area's fourth de-icing system is scheduled to be operational by 2008 in Detroit Lakes. The system will cover a 300- to 400-foot stretch of Highway 59 over two railroads through the intersection of Highway 10.
Construction on the estimated $37.3 million, four-year Highway 10 project through Detroit Lakes begins this spring.
The project includes reconstruction and realignment of three miles of Highway 10 and one half-mile of Highway 59 between highways 10 and 34. It also includes expanding Highway 59 to five lanes and a stoplight at the intersection of Highway 59 and Highway 34.
Readers can reach Forum reporter Joe Whetham at (701) 241-5557