The Iowa Department of Transportation has awarded the contract to build the new Interstate-74 bridge to Wisconsin-based Lunda Construction Co. for about $322.1 million.

The Iowa Department of Transportation said Wednesday that it has awarded the contract to build the new Interstate-74 bridge to Wisconsin-based Lunda Construction Co.

The DOT said the contract is for about $322.1 million. The next lowest bid was at $357.8 million.

It's not clear yet precisely when work on the bridge will begin. Sam Shea, a transportation planner for the Iowa DOT, said Wednesday he had not seen a schedule yet, but that work likely would begin in the Mississippi River by sometime next month. "I imagine they'll have quite a bit of staging to do," he said. Most of it will be in downtown Bettendorf.

Shea said people will likely see barges in the river fairly quickly, but that as far as anything being erected in the water, that is likely a few months away.

Construction of the bridge is expected to take three years. Much of the impact to traffic will be in 2019 and 2020. The project consists of two bridges, each about 3,400 in length, with two 795-foot basket handle arches over the Mississippi River navigational channel.

Selecting a contractor is a key milepost in the Interstate-74 corridor project, which has been in the planning stages for years.

Lunda, which is based in Black River Falls, Wisconsin, could not be immediately reached for comment Wednesday afternoon. But the company's web site cited work it's done on a number of bridges in Wisconsin and Minnesota, including in the Minneapolis/St. Paul area. Lunda was founded in 1938. It's now a subsidiary of Tutor Perini, a large construction firm based in the Los Angeles area.

The $322 million bid came in significantly less than the DOT had anticipated. It had estimated that the I-74 project would cost between $400 million and $450 million, which included a viaduct and off-ramp over downtown Bettendorf estimated at about $30 million. A contract for that work has not been announced yet, Shea said.

Despite the savings, the project still is the largest contract the state DOT has ever awarded, Shea said. He added the local share of the contract's cost came in somewhat higher than expected, but he did not have a figure available Wednesday afternoon. The cities of Moline and Bettendorf are responsible for those costs.

Bettendorf City Administrator Decker Ploehn said Wednesday the city was expecting to pay $14 million for its share. "I think this is up a couple hundred thousand over that," he said.

Ploehn said he didn't consider it a major problem, but that the city is talking to the DOT about why it happened and is hoping to lower the amount.

Wednesday's award is the first of a number of I-74 related contracts that will be handed out this summer.

The state of Illinois is expected to award a contract in June for work from the river to 7th Avenue in Moline, which will include the viaduct over downtown and street improvements to accommodate the interchanges. That's estimated at $120 million. Then, probably in September, contracts will be awarded for work on the interstate from 7th Avenue to just south of Avenue of the Cities, as well as street improvements, including reconstruction of 19th Street. That work has been estimated at $128 million.