The Eisenhower Bridge of Valor is a vital new piece of infrastructure spanning the Mississippi River between Wisconsin and Minnesota. The project fully replaced a cantilever bridge, which opened in 1960 and was recently determined to be “fracture critical.”
The old bridge was the only river crossing for 30 miles and accommodated more than 13,000 vehicles every day, so the replacement process had to be minimally disruptive and cost effective. Those priorities drew the design team to precast concrete.
“Precast concrete I-girders are the bread-and-butter superstructure that MnDOT uses for a variety of reasons largely related to cost, simplicity in construction, durability, and low maintenance,” says Ben Jilk, complex analysis and modeling engineer for the Minnesota Department of Transportation (MnDOT) Bridge Office. Additionally, the use of prestressed concrete helped the project meet federal environmental assessment standards, which required that the project not significantly affect the local environment.
The design features a seven-span precast concrete bridge composed of four spans of 174 ft 82 in. , and 202,000-lb prestressed girders. At the time of production, the 174-ft-long concrete girders were the longest in the state. Their massive size and high-performance strength outmatched alternative materials and proved ideal for this substantial project, Jilk says. “The newer shapes allow us to span longer distances with our precast concrete bridges and help reduce the number of piers needed.”
From Janesville to Red Wing
To produce the long spans, crews had to perform production activities from elevated work surfaces, which required specialized scaffolds and lifts. Once cast, the precaster safely hauled the massive bridge girders 280 miles from Janesville, Wisc., to Red Wing, Minn. “The total length of loads reached 220 ft, combining the girder, truck, and six-axle rear-steer trailer,” says Gary Courneya, plant operations manager for County Materials Corporation.
To minimize disruption to traffic, the new bridge was constructed next to the existing structure over a busy rail corridor and waterway. A 1000-ft-long causeway and 43-ft-deep cofferdam were created to access the site.
The spans were installed above the land leading up to the river, with three spans of steel tub girders, measuring 218, 432, and 292 ft, spanning the river. Crews worked from barges and performed frequent critical crane lifts to overcome staging obstacles.
To keep the project on schedule, two cranes were used to set prestressed girders during 45-minute windows, which dramatically minimized the need for road closures.
After two years of construction, the bridge opened for traffic in 2019. It features two travel lanes, wide shoulders, a shared-use biking and walking path, and 1640-ft-long spans. “This was a special project because it was built in an iconic town, and it provided a unique opportunity for MnDOT and the Wisconsin Department of Transportation to collaborate,” Jilk says.