Our team is providing environmental documentation and design engineering services for the replacement of the historic Black Hawk Bridge over the Mississippi River at Lansing, Iowa.
The existing 1,626-foot bridge, built in 1931, includes a 1,126-foot cantilever truss structure and provides a vital connection between Iowa and Wisconsin and spans Lower Pool 9 of the Upper Mississippi National Wildlife Refuge. The project team brings extensive experience in the National Environmental Policy Act (NEPA) process, wetlands, endangered species, river hydraulics, and design and constructability of major river bridges to address key issues and opportunities:
Designing for constructability — The project requires special consideration of constructability based on river geometry and limited staging areas. The team is leveraging its experience on more than 30 major river bridges, including specific experience with on-site float-in design and construction.
Mitigating impacts to the environment — The environmental team is working closely with agencies and local stakeholders to define the Purpose and Need and evaluate alternatives that consider the historic nature of the bridge, wetlands and wildlife habitat, local cultural sites, and impacts to the local economy. The design team has also proposed an alignment alternative that minimizes the structure length and avoids the most sensitive wetlands near the project.
Preserving the historic nature of the bridge — This project presents an opportunity to save a piece of the existing bridge while enhancing the local environment. The team has proposed ideas for preserving the existing west abutment, first pier and a portion of the existing truss to incorporate them into a scenic overlook that tells the story of the historic bridge.