Built in 1873, the Kern Bridge was a single-span, bowstring arch bridge spanning the Le Sueur River in Blue Earth County. The bridge was the only bowstring through truss bridge in Minnesota and at 189’ in length was the longest existing bowstring bridge in the U.S. The bridge needed to be removed for safety, and was dismantled and stored in the winter of 2020 for eventual relocation and reuse as a pedestrian bridge.

Rani Engineering was the contractor’s structural and civil engineer for the work that led to the safe and methodical dismantling of the bridge, including development of plans for disassembly, shoring, lift sequencing, cataloguing of pieces, and a coffer dam and access road for the crane. Rani also performed pre-lift inspections of the bridge.

The complexity of this project is evident in the great lengths required to avoid damaging or modifying the structure prior to lifting the bridge and placing it on cribbing where it could be carefully and properly marked and disassembled for storage. Rani’s structural engineers were tasked with meeting with the contractor and crane company and putting their vision and ideas through rigorous examination. Through this process of documenting and designing, Rani provided valuable technical insight, ideas, and feedback that would make the process safer and more efficient while maintaining the integrity of this valuable piece of Minnesota history.