The Idaho Transportation Department is going back to the drawing board on its winter traffic plan for a 3.75-mile construction zone on state Highway 75 south of Ketchum.
The problem, explained Devin Rigby, district engineer for ITD District 4, is there is no place for water to drain in the deep ditches that were left for the winter by construction contractor Idaho Sand and Gravel Co. along much of the construction zone before work was halted for the season.
“This is one of the most difficult challenges we’re going to face this winter,” Rigby said at a Thursday meeting of the Blaine County Regional Transportation Committee. “Right or wrong, we’re here. We have the option now to fill those in.”
“On paper, it doesn’t look near as bad as it does in the field. Once you look at it, it’s a ditch.”
The ditches, in areas up to 4 feet deep, mostly on the west side of the highway in the construction zone, have been raised as an issue by the public as a factor that could turn winter vehicle slide-offs into a more severe accident, especially if a vehicle ends up upside down and partly submerged in water.
Rigby said ITD hasn’t decided how to deal with the ditch issue yet, but that something has to be done to mitigate the problem of water retention. He said the most likely option is to fill the ditches with gravel, so that water will be retained underground or will run off to the side away from the highway.
“We have to do something,” Rigby said. “On paper, it doesn’t look near as bad as it does in the field. Once you look at it, it’s a ditch.”
Rigby said ITD agreed to the winter traffic plan in the construction zone as a way of saving earmarked funds for the Highway 75 expansion plan. Funding has been allocated to complete the 3.75-mile expansion project south of Ketchum and to replace the bridge over the Big Wood River near St. Luke’s hospital so that it could accommodate four lanes of traffic.
But filling in the ditches, Rigby said, “will probably eliminate our ability to build bridges.”
The construction zone runs from Timber Way just north of East Fork Road to the bridge near St. Luke’s. When finished next year, the highway will have two lanes in both directions.