It is the rare project of construction of the bridge that has no challenges. But building a new Mississippi River bridge between Lansing, Iowa and Rural Wisconsin is demonstrating more problematic than most, testing the project team wit and the patience of travelers in a zone without any convenient alternative change.
Since breaking the 1,724 -foot steel terrain through the Truss bridge in October 2023, the Kraemer North America contractor has had to stop the main constructions on several occasions when the movement of the structure of almost an existing century, located only 75 feet away, has exceeded the safety thresholds.
Following the last incident this May, the battery driving activity for the new bridge has remained in awaiting in early July. It was considered that the old bridge was reopened to traffic, waiting for a technical analysis that will determine how and if it can coexist with the adjacent construction work.
The existing structure, known as the Black Hawk bridge or the Lansing Bridge, opened in the 1930’s and is a well -known milestone in the area.
Photo courtesy of Kraemer North America
Aaron Rosenbery, responsible for the Kraemer’s project, estimates that interruptions at the end of June had added more than 100 days to the design project of $ 140 million. “It has had a domino effect on our critical path,” says Rosenbery on the last stop, which stopped the installation of traffic towers to support the new transits on the bridge. “We had expected to start steel erection in mid -July,” he says, “but we can’t bring steel if we don’t have the plot.”
Also called Black Hawk Bridge, the structure through Truss was built in 1931 by a private company, with the states of Iowa and Wisconsin, assuming joint property in the mid -1950’s.
Clayton Burke, project manager of the Iowa Department of Transport, explains that, while the agency has collected extensive data on the current condition of the existing bridge, the information on its past has been more difficult.
A receiving cage rises with a 250 tonne crane and then installed on the floor where concrete is placed to form the axis of perforation, one of the three axes to support the wharf of the bridge.
“There is no construction and we have assumed it to be founded in wood piles that are probably only about 40 meters deep,” he says.
Although the points could have preferred a greater separation between new and old structures, location restrictions such as culturally rich and environmental areas needed nearby barracks. “We ended up building in a very tight area,” says Burke.
Given the state of the bridge as a local milestone, the community was very much dedicated to shaping its replacement. Parsons of designers and engineers housed those feelings with a design that, at least, mimics the original through the Truss configuration, although with concrete pilasters resting on 11.5 feet-day concrete axes driven up to 150 feet to the base and with a 40-foot cover to adapt to the larger tracks and the 8-foot belts.
Greg Hasbrouck, technical director of the Parson complex bridge, says that design replicates the Cantilever traffic of the original structure, but the longest of 778 feet and the lateral linking of Iowa led to a Asymmetric SPAN design, as well as a unique construction sequence to eliminate the rise from the back of Truss.
The new bridge will have wider lanes to adapt to more traffic.
Iowa’s Department of Transportation Department Courtesia
Due to a sharp turn to the river nearby, add Hasbrouck, the United States Coast Guard requested additional authorization for the navigation channel. “Large ship impact design loads and a space tight between the navigation channel and the Iowa Bank railway required a single row of large diameter axes so that these foundations work,” he says.
The design also incorporates several redundancy strategies that will help save money in the future with inspection protocols. “It adds the certainty that traffic will remain stable if a steel fissure occurs,” adds Hasbrouck.
Kraemer’s construction strategy was to start from the river Wisconsin and work west. The control teams installed on the existing bridge along with the field polls helped the project team to maintain a clock around the stability of the structure as the work progressed. While some movement was recorded during cleaning and traffic on the east coast, the bridge remained relatively stable during the installation of the sheet pile in preparation for the vibration hammers to pierce three foundation axes for each of the first two pillars.
A minor movement was expected, according to Rosenbery, given the length of the structure and the large amount of steel.
“Although the last 20 to 30 years of surveys have documented cycles of vertical and lateral movement, it was smart to have a short threshold to ensure that our work has no negative effect,” he says.
The construction team stopped construction on several occasions when the existing bridge movement exceeded security thresholds.
Iowa’s Department of Transportation Department Courtesia
It was during the installation of the Substructure of the Wisconsin three floors in February 2024 that the security threshold was exceeded. Rosenbery says that, although the vibration of this process was minimal, the small amount of compression and decompression of the soil altered the underground stability of the piles of shallow wood, giving rise to about 8 inches of accumulated movement in the existing Wisconsin approach. With the movement that triggered an immediate closure of the old bridge, the project team went back to developing a solution to return to the bridge in service.
After raising four subsequent shifts’ segments with a total of 320 feet from its supports, Kramer replaced the old wooden piles with new 9 -foot pierced holes for temporary steel beings with 35 -foot rock plugs in depth leading about 150 feet to the base. Then the segments were replaced and secured, allowing Iowa Dot to reopen the bridge to traffic in just two months.
Burke estimates that the repair strategy added $ 1.5 million to the cost of the project, but it was worth keeping the traffic interruptions at least. The absence of alternative crossings means that motorists face a detour in the rural area of almost 70 kilometers. “There is about 90 minutes in the best of conditions,” he says, “and even longer if there is another construction along the way.”
The Kraemer’s strategy in North America was to begin construction on the Wisconsin side and move to the west.
Iowa’s Department of Transportation Department Courtesia
The welcome resumption of construction was short, as the record floods in early summer put a dam for almost three weeks on the program. “The river was at a speed and elevation that they could not work safely on the channel, which is where we have to be,” says Rosenbery. “It was a substantial impact, but we couldn’t do it.”
Kraemer was able to regain his impulse for the rest of the year, pierce the axes and pour concrete for the remaining wharf feet and the abutment on the west side. As a precaution, the existing bridge was closed during the installation of casings for Moll 2, the only support of the new bridge located in the water. After learning from the difficulties of maintaining a hole open for the facilities of the drilling axis, “the solution was to drive the housing axes for the style of 2 inches, excavate and add, push down, cut, excavate, adding progressively,” says Rosenbery. “It took time, but it worked.”
Despite the challenges, it is currently expected to open the new bridge for mid -2017.
Iowa’s Department of Transportation Department Courtesia
In the first months of 2025, Kramer was setting the 5 -foot tall beams, 121 feet in length in the three piles of Wisconsin and prepared for the roof. Next to the Iowa, a ringer crane began on the barge in the 60 -foot columns for the pores of the river and the coast.
Once the complete construction is resumed, the plans ask that the backspar and traffic end, with the construction of cantilever from the Piers 2 and 3 to cover the navigation channel. A central section of 334 feet in length will be lifted from a barge to complete the passage. The project is currently planned for the mid -2017.
