Sault Ste. Marie International Railroad Bridge

Gray & Pape completed Historic American Engineering Record documentation of the Sault Ste. Marie International Railroad Bridge in Sault Ste. Marie, Michigan, spanning the Soo Locks at the St. Mary’s Falls Canal. Originally built in 1887 and modified in 1913 and 1959, the current owner of the railroad bridge is the Canadian National Railroad. The Sault Ste. Marie International Railroad Bridge has nine camelback truss spans crossing the St. Mary’s River with bascule and vertical lift bridge components crossing the American Locks at the St. Mary’s Falls Canal. It is the only bridge in the United States known to include these three types of spans in a single structure. In addition, the bridge was the first structure to use an interlocking mechanism to connect the leaves of the double-leaf bascule span. The International Railroad Bridge represents a nationally significant engineering structure and is Michigan’s most significant railroad bridge from an engineering history standpoint. Proposed alterations would result in the demolition of much of the bridge and alter the historic environment of the St. Marys Falls Canal. As a result, the International Railroad Bridge was documented according to HAER standards prior to alterations to the Warren truss spans. The documentation created a permanent record of the bridge’s engineering and appearance and was undertaken as part of a Memorandum of Agreement between the Corps of Engineers, Detroit District, and the Michigan State Historic Preservation Office.