BATH — The viaduct that carries U.S. Route 1 traffic over the heart of the city will close later this year for reconstruction.

Under the state’s plan, the structure can’t be closed until Oct. 11, and must reopen no later than Memorial Day 2017, Maine Department of Transportation project manager Joel Kittredge. All work must be completed by June 30, 2017.

“The superstructure is going to be torn down, right down to the ground,” Kittredge said. “And then it will be rebuilt.”

Preliminary work will begin in April on Washington Street intersections, frontage roads and drainage, Kittredge said. The viaduct will remain open during that time, and no work will be done during Heritage Days in July.

Four pre-qualified contractors can bid on the project: Cianbro, CPM Contractors, Reed & Reed, and Wyman & Simpson. Bids are scheduled to be opened Feb. 17.

The two-lane viaduct is a quarter-mile long, from High Street to the Sagadahoc Bridge, running past Bath Iron Works. The structure was last closed in 2007, with traffic rerouted to Leeman Highway and Commercial Street, while a new surface was applied.

The same detour will be used this time.

The total project cost is $15.1 million, including $1.9 million for preliminary engineering, $12.7 million for construction and $500,000 for construction engineering, according to Kittredge. Federal and state funds are going into the project.

The bridge, built in 1958, has a superstructure that has reached the end of its useful life and needs more comprehensive work, Kittredge said in a 2014 interview. The superstructure will be replaced.

While most of the viaduct’s piers — which support the load — at first were expected to remain in place and be rehabilitated or repaired, further analysis of construction, engineering and economics has led to a decision to replace all of them.

The reconstructed viaduct will not have additional travel lanes, and should last at least 50 years, Kittredge said.

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