Collaboration and cooperation has work on construction of the replacement Interstate 74 Mississippi River Bridge in Iowa and Illinois running smoothly and on time and within budget.

"I am amazed at the coordination between two DOTs, multiple contractors and local agencies," says David von Kaenel, an Engineer with the Illinois Department of Transportation. "Everyone is pulling on the same end of the rope, with the same goal."

The existing westbound Illinois to Iowa structure opened in 1935, designed for a capacity of 48,000 vehicles per day, and the eastbound Iowa to Illinois bridge was built in 1960. Neither structure has shoulders, so traffic comes to a standstill when there is an accident.

The bridges, with two 11-foot-wide lanes in each direction, carry about 80,000 vehicles daily, with volume expected to increase by 2035 to 99,900 vehicles daily, due to population growth.

"The area has outgrown the existing structures," says Danielle Mulholland, I-74 Project Manager for the Iowa DOT.

The Iowa and Illinois departments of transportation are jointly building the project. The new bridge will be built east of the existing alignment, to minimize disruptions to traffic. The north side is within 150 feet of the old bridge, and at the south end, the old and new bridges are about 1,000 feet apart. The new bridge will have four 12-foot lanes in each direction and shoulders.

The $1.2 billion, 6-mile-long project is considered a key element of a regional strategy to improve access in the Quad Cities area. In addition to the bridge, expected to be complete in 2020, the project includes reconfigurations of interchanges and roadway improvements. The bridge will feature bike and pedestrian access. Removal of the old bridges will take place in 2021.

A Landmark Structure

The departments have been working on a bridge replacement for about 20 years, von Kaenel says. There have been multiple community meetings on both sides of the river. Additionally, a committee of transportation and community officials collaborated throughout the planning phase. The federal government approved the project in 2009. Right-of-way acquisition and roadway realignment began in 2013.

Modjeski and Masters of Mechanicsburg, Pennsylvania, as part of the Alfred Benesch of Chicago design team, completed the final design of the arch. Modjeski and Masters designed the original bridge in 1933 and the twinned structure in 1959. Bensch of Chicago designed the approaches, from each end of the arch to roughly each bank of the river.

After much community input, the transportation departments selected a true-arch bridge with dual basket handle-style steel arches. Citizens wanted a landmark structure, and this delivers while maintaining the budget. The 3,400-foot-long bridge will cost about $325 million.

"It will be the only true-arch bridge that spans the Mississippi when this is complete," Mulholland reports.

The water is about 15-feet deep where the piers are placed, so it has a shallow foundation, drilled shafts supported on bedrock. Fourteen sets of piers will be placed in Iowa. The true arch will have a 795-foot span across the navigation channel. The bridge will have steel girders for the approaches, and the arches are steel.

"It is simply stunning," von Kaenel adds.

A Fast-Paced Project

Iowa has taken the lead on the bridge portion of the contract.

"It was an eight- to 10-year schedule, compressed to five years and now to three and a half years," Mulholland says. "We are not completing work in succession, one contractor at a time. It's all occurring simultaneously and that required cooperation between the contractors and the states."

Work began in July of last year. Lunda Construction Co. of Black River Falls, Wisconsin, received two contracts for the bridge work - one for the arches and one for the approaches. The steel arches are being fabricated.

"It's a fast-tract project," Mulholland says. "The river adds to the challenge of building in a tight time frame." 

Lunda has dredged the river to reach a solid base for the piers. Crews are working off between 40 and 50 barges, year round. von Kaenel estimated 10 cranes were working on the project in December. Lunda placed cofferdams around each pier to keep the area dry and safe for workers.

Mulholland explains that there was no way to add fill during construction, so Lunda had to put drilling equipment, cranes, supplies and everything needed for the project on barges. Small boats take supplies as needed between barges.

"It's quite a site," Mulholland says. "Everything is floating on a barge. We think more about windy days on the water than we would otherwise."

Looking forward, tying into the existing highway will require careful staging, von Kaenel says. Different projects will reconstruct the existing roadway within its current alignment. In the summer of 2019, for three months, westbound/northbound traffic on the Illinois side will be detoured to local roads and then drivers will be able to access the interstate again before continuing to Iowa.

Two additional projects on the Illinois side will cost $85 million and $83.7 million. That work will realign I-74, so it lines up with the new bridge. The contractors are Kraemer North America of Plain, Wisconsin, working closest to the river and on the $85 million package, and Walsh Construction of Chicago will expand I-74 to three lanes on the 2.5-mile segment to the south between Seventh Avenue and Avenue of the Cities in Moline, Illinois. Construction will start early this year.

On the Iowa side, Iowa Civil Contracting of Victor, Iowa, has a $30 million contract for the land spans. Iowa DOT has three more contracts to let.

The seven contractors and two transportation departments are working closely and coordinating with a consultant, led by AMEC, providing general oversight.

"I hope when we are all done, everyone drives through and says, "˜They left it better than they found it,'" von Kaenel says. "This will be functional and beautiful."