The iconic Keystone Bridge in Elkader, Iowa, was built in 1889 to provide the city with a long-lasting river crossing solution. Before its construction, several timber and iron bridges were built to cross the Turkey River, but they all deteriorated rather quickly and were found structurally unsafe within a decade of their construction. In 1888, the city decided to replace the latest iron truss bridge with a more durable stone arch bridge. The historic bridge, one of the largest and best constructed twin arched stone bridges in the Midwest United States, has seen numerous repair campaigns over time but continuing material deterioration and the appearance of longitudinal cracks in each of the two arches prompted a low load posting of 5 tons. In 2015, the City of Elkader initiated plans for what was set to be the most extensive rehabilitation of the bridge since its construction in 1889. The city identified the AASHTO HS20 truck and the Iowa DOT legal vehicles as the target live loads for the rehabilitation. Construction started in April 2022; the structural repair scope of work included a new cast-in-place reinforced concrete deck, a new cantilever sidewalk attached to one of the spandrel walls, pinning of the spandrel walls, and stone masonry repair and strengthening to increase the longevity and load carrying capacity of the bridge to meet current design loads.
Read the entire article here.