WATERLOO — The rebuilding of U.S. Highway 63 through downtown is expected to get underway in the spring.

The Iowa Department of Transportation is working to finalize contract details to reconstruct Mullan Avenue and First Street, the one-way couplet serving as the highway, between Jefferson and Franklin streets.

Langman Construction Inc., of Rock Island, Ill., was the low bidder on the project in late December at just more than $19.4 million.

While the bid was higher than expected, Wes Musgrave, who oversees IDOT’s contracts office, said the price was within 20 percent of a second bid of $21.2 million from Peterson Contractors Inc., of Reinbeck.

“The fact that we received two competitive bids, and given that the project cost and risks would likely only increase by rejecting all bids and re-advertising the work at a later date, all factored into the decision to award,” Musgrave said.

Federal and state highway dollars are covering the bulk of the U.S. 63 reconstruction, which is being completed in multiple phases.

Work on the original phase from Newell Street north to Donald Street, near UnityPoint-Allen Hospital, wrapped up in 2016.

Pete Hjelmstad, IDOT Disrict 2 field services coordinator, expects bids to be opened in March for the third phase between Franklin and Newell streets. That segment includes building an overpass to replace the current flood-prone Canadian National Railway underpass.

Work on both phases will start in the spring and run through November 2018, taking a break over the winter months next year, Hjelmstad said. The late state date on the Langman Construction Inc. contact is April 23, 2017.

Work on the downton portion of the project will be done under traffic. But the future construction of the railroad overpass will require a detour between Franklin and Newell streets.

Waterloo City Engineer Eric Thorson was waiting to hear from the DOT about the city’s share of the work.

“We pay for the street lighting, decorative pavers at some intersections, some sidewalk expense and a portion of the storm sewer,” Thorson said. “They pay for the traffic signals and the paving.”

The Waterloo Water Works also must pay for water main replacement.

The project replaces the highway paving on both sides of the Cedar River but not the bridges. Additional storm sewer work was designed to help alleviate street flooding which has plagued the area on the west side of the river for many years.