Sparking Curiosity: HLR Inspires Future Engineers at the U-46 Explore Event

Hampton, Lenzini and Renwick, Inc. (HLR), in partnership with the City of St. Francisville, is proud to announce that the Wabash Cannonball Overflow Bridge Replacement has received a 2026 Engineering Excellence Special Achievement Award from the American Council of Engineering Companies of Illinois (ACEC-Illinois) . This recognition honors projects that demonstrate exceptional engineering achievement, innovation, and public benefit, and the Wabash Cannonball Overflow Bridge Replacement stands as a powerful example of how thoughtful design can strengthen infrastructure while protecting sensitive natural environments. Replacing a Critical Lifeline The original bridge, a 1,100-foot timber trestle converted decades ago from a former railroad structure, had reached the end of its service life. Its narrow, one-lane configuration and severe deterioration posed growing safety risks and maintenance challenges for the City. As a vital connector between Illinois and Indiana across the Wabash River floodplain, the bridge plays a critical role in emergency response, commerce, and daily travel for residents and businesses. Recognizing the importance of this crossing, the City partnered with HLR to deliver a long-term solution that balanced structural performance, environmental stewardship, and community needs. Innovative Design in a Sensitive Environment HLR designed a new 1,030-foot precast concrete girder bridge constructed parallel to the existing structure and built in two stages to maintain traffic throughout construction. The new bridge features longer spans and fewer piers, reducing scour risk, debris accumulation, and long-term maintenance demands, key advantages in a dynamic floodplain environment. Precast concrete girders were selected over steel to provide greater durability, corrosion resistance, and life-cycle cost savings for the City, ensuring the bridge will serve the region reliably for generations. Environmental Stewardship as a Core Design Element Environmental coordination was central to the project’s success. Fourteen wetlands were identified within the project area, with impacts minimized to less than half an acre. When no wetland mitigation bank credits were available in the watershed, HLR developed a 5-acre forested mitigation wetland on City-owned land nearby, transforming a regulatory challenge into a lasting environmental asset. The project also required careful protection of threatened species, including the state-endangered bloodleaf and the eastern ribbon snake. Close coordination with the Illinois Department of Natural Resources, U.S. Army Corps of Engineers, and other agencies ensured full compliance while preserving sensitive habitats. Engineering Ingenuity from Start to Finish Tight environmental constraints and limited site access required creative construction solutions. Concrete piers were placed using the existing bridge as a work platform, minimizing disturbance to surrounding wetlands while maintaining continuous traffic. Despite complex permitting and pandemic-era agency coordination challenges, the project was completed on time and within budget. A Model of Balanced Engineering Excellence The ACEC-Illinois Special Achievement Award recognizes the Wabash Cannonball Overflow Bridge Replacement as a project that goes beyond structural design, demonstrating how engineering can connect communities, protect natural resources, and deliver lasting public value. HLR is proud to have partnered with the City of St. Francisville on a project that r eflects the firm’s commitment to innovative design, environmental responsibility, and resilient infrastructure .