The bridge problem for a state like Iowa (with the most problem bridges) is not a big deal. Basically most of these deficient bridges are on farm roads and carry very little traffic (less than 100 vehicles a day). The bridges are restricted so only one heavy vehicle is allowed on the bridge at one time--but with less than 100 vehicles a day this rarely happens--and in those rare occasions where it might happen it is not a problem to wait until the other vehicle has crossed.