CTH M Bridge Replacement

Challenge

Built in 1955, the County Trunk Highway (CTH) M Bridge was deteriorated, corroded, and deemed functionally obsolete, posing safety concerns. As the largest county-owned bridge in La Crosse County, Wisconsin, this high-profile structure crosses the environmentally sensitive La Crosse River, requiring special care and thoughtful hydraulic design to handle flood events. This structure also had to meet the diverse needs of the commuter and agricultural area, such as wider lanes for hauling and equipment movement, along with bicycle and pedestrian amenities.

Solution

To address the complex challenges associated with this deteriorated structure, the La Crosse County Highway Department enlisted the design expertise of SEH engineers. Funded through the Wisconsin Department of Transportation (WisDOT) Local Bridge Program, the project included pavement replacement, approach improvements, and the restoration of shoulders and ditches.  

Addressing a steep roadway and tight area constraints, the project required thorough geotechnical analysis due to diverse substructures supported on spread footing and piling. It included prestressed girder, abutment, pier, deck design, and extensive slope erosion control. The design team also successfully navigated challenges related to utility relocations, right-of-way impacts, and the relocation of an existing private drive near the end of the bridge.  

The presence of the La Crosse River and natural resources surrounding the project required careful consideration of environmental factors, leading to extensive interactions with regulatory bodies. Project coordination involved the public, utility companies, WisDOT, Wisconsin DNR, and the U.S. Army Corp of Engineers.  Incorporating visualizations, such as a 3D animated rendering, allowed stakeholders to virtually experience the improvements long before construction, fostering a deeper understanding and support for the project.  

By effectively overseeing the project's design, SEH met schedule and budget constraints, ultimately enhancing the bridge’s quality and safety for the community of La Crosse. The project is expected to be completed by fall of 2024.