Plymouth Avenue Bridge
The Plymouth Avenue Bridge is a segmental bridge that spans the Mississippi River in Minneapolis, Minnesota. It was built in 1983 and was designed by VanDoren-Hazard-Stallings. The construction of this bridge was unique, for it was the first segmental concrete girder bridge built in Minnesota. This method of design uses a "form traveler" that shapes the concrete as it is built out from the piers. This avoided the use of falsework and avoided impeding river traffic. The concrete is also engineered to be salt-resistant by the use of post-tensioning. Tubes run through the concrete structure carrying strands of cable. With tension on the cables, the structure is designed to be under compression. This prevents cracks and hinders the intrusion of salt water. Since then, other bridges in Minnesota have used this construction method, including the Wabasha Street Bridge in downtown St. Paul, Minnesota and the Wakota Bridge in South St. Paul, Minnesota. The original bridge was a wooden Howe truss design, built in 1873. This was built when Minneapolis, then only on the west side of the river, consolidated with the city of St. Anthony, on the east side of the river. As part of the merger, Minneapolis (the western city) agreed to build two bridges, one upstream of the Hennepin Avenue Bridge and one downstream. That bridge was replaced in 1886 with an iron truss bridge. It was remodeled in 1913 and then raised in 1953 for more clearance. As a result of deterioration over the years, the bridge was closed in 1981 because the floor beams were rusted. On Friday, October 22, 2010, the Plymouth Avenue Bridge was closed indefinitely "as a precaution, pending further investigation after a routine inspection discovered corrosion on cables that run through the bridge."

Bridges of the Mississippi River