When I was in the army which seems like an eternity ago now, they had trucks that could make a bridge within hours. The bridges were floating so wouldn't be useful here as there is alot of boat traffic.
But we are only taking a span of 60ft and over land, you could demo that whole thing in a couple of days and then use two or three of these guys to fill the gap while you contruct a new span.
They are 26m in length and able to deploy in 8minutes and can withstand more weight then the current bridge could. Unfortunately they belong to Norway and we don't own any.