The Michigan Street Bridge in Sturgeon Bay will be shut down for 18 days, beginning Tuesday. The Department of Transportation says the more than 80-year old span will be closed at noon Tuesday as part of a project to repair nine bridge beams damaged in a vehicle strike on April 22nd. A backhoe being towed by a semi-truck struck the bridge superstructure as it was being transported across the downtown structure. The repairs will cost about $200,000 to complete and consist of cutting the damaged beams out and bolting new beams in place. The DOT used three dimensional imaging technology to create specifications for prefabrication of new beams to exactly replicate the damaged beams. An off-site facility prefabricated the replacement parts and transported them to Sturgeon Bay for repair when the shipping season ended. The state agency says repairing the bridge in winter lessens the impact for marine and motor vehicle traffic. All of the repair work is weather dependent. The bridge will continue to open for marine traffic while repairs take place. All repair costs are the responsibility of the driver of the semi towing the backhoe which damaged the bridge.