FAIRBANKS -- A proposed $160 million railroad bridge across the Tanana River that will be the largest in Alaska is already posing challenges in the planning stage.
The bridge will be more than a half-mile long and connect the highway near Salcha to 1.2 million acres of military training ground south of the river, The Fairbanks Daily News-Miner reported.
The bridge will accommodate trucks and trains, with rail embedded in the roadway. It's the first stage in an 80-mile, $700-plus million expansion of the railroad to Delta Junction from its endpoint at Eielson Air Force Base.
The area near Salcha now can be reached only by ice bridge or aircraft.
Brian Lindamood, a project manager for the Alaska Railroad Corp., said there are many variables in the final plan, including where to build the steel beams needed when construction begins.
Lindamood said each of the 80 beams will be 12 feet high, 165 feet long and weigh 60 tons.
The bridge will sit on hammerhead, 10-foot-diameter column foundations. Each of those will in turn rest on a 576-square-foot pad supported by 6-foot-diameter pilings sunk 110 feet into the riverbed.
"With piles that size, you don't just go out and get a regular pile driving hammer," Lindamood said. A big one is needed. "There's a handful of them floating around the world. The last time we checked, the nearest one was in Singapore."
Contractors will also need to find huge rocks to buttress the northern riverbank.
Construction is set to start next year and last into 2015. Once it begins, it could put up to 150 workers on the job on a daily basis.
"We're going to be spending six figures a month just to keep the lights on out there," Lindamood said.
The bridge's tentative lead contractor is Nebraska-based Kiewit, although contract negotiations continue.
The newspaper reported the project is all but financed, given a series of federal grants and one from the state Legislature. A final price tag should arrive by year's end.