|Bridge Name||Facility Carried / Feature Intersected||Location||Structure Type||Construction Date and Builder/Engineer|
||I-75 / TC-17B Over St. Marys River and Associated Canal System||Sault Ste. Marie: Chippewa County, Michigan and Algoma District, Ontario||Metal Cantilever (Suspended Deck) Bolt-Connected Warren Through Truss, Fixed and Approach Spans: Metal 8 Panel Bolt-Connected Warren Deck Truss, Fixed||1962 By Builder/Contractor: Unknown and Engineer/Design: Steinman, Boynton, Gronquist and London of New York, New York|
|Main Span Length||Structure Length||Roadway Width||Main Spans||Approach Spans||NBI Number|
|430 Feet (131 Meters)||9280.6 Feet (2828.7 Meters)||28 Feet (8.53 Meters)||7||56||17117034000B010|
Although perhaps the most well-known and visible bridge in Sault Ste Marie, from a historical perspective, this is the least significant of the bridges, when compared to the International Railroad Bridge, and the Emergency Swing Span, and the Ashmun Street Bridge
This bridge is a complex structure. The minor spans are all deck plate girder spans. There is a deck truss span over the Power Canal on the Michigan side. The span over the U.S. canals is a two-span through arch. The span over the Ontario canal is a single span through arch. The bridge is noted for its sag in between these two through arch spans, which was done because under-bridge clearance was not a concern at that part and so to reduce costs, the piers were built with a lower height there. The International Bridge lacks any v-lacing or lattice, and all connections are bolted. There are rivets on the built-up beams however. The concrete piers are tall and impressive, but feature minimal aesthetics, especially when compared to a bridge like the Blue Water Bridge.
Information and Findings From Michigan Historic Bridge Inventory
This is one of Michigan's five monumental bridges. The twin cities of Sault Ste. Marie in Michigan and Ontario were linked by a railroad bridge in 1887, but automobile traffic between the cities was carried by ferry until this bridge was opened in 1962. An International Bridge Authority was created by the Michigan State Legislature and passed before construction was begun.
It was designed by the firm of Steinman, Boyton, Gronquist, and London of New York and cost twenty million dollars. This bridge was an ambitious project because it crossed two navigation canals and the St. Mary's River.Overall, the bridge is 2.76 miles long, including approaches, and provides a two lane roadway 28 feet wide. The Main spans had to be erected without the use of falsework so as not to obstruct traffic through the American and Canadian Locks. This was done through the balanced addition of steel structural members on the main spans.
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