Yankton U.S. 81 bridge requires maximum weight limit Based on a recent routine bridge inspection, certain elements of the Yankton Bridge were found to be experiencing corrosion, leading to a 10-ton maximum weight limit. Vehicles exceeding 10 tons gross vehicle weight will be required to take an alternate route. The nearest Missouri River crossings are located east over the New Castle/Vermillion Bridge on Highway N-15 (South Dakota 19); and on N-12 (South Dakota 37) to the west over the Niobrara/Springfield, Standing Bear Bridge. This maximum weight limit is anticipated to be temporary as engineers design a permanent repair.               return