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Lafayette Bascule Bridge Replacement Peer Review

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The Lafayette Street Bridge is one of a set of three bridges located in Bay City, Michigan. It carries M-13 and M-84 over the Saginaw River and is the oldest of Bay City's four modern bascule bridges. The existing main span is a Scherzer double leaf rolling bascule that provides a 150 foot (ft.) navigable channel, and the approach spans consist of a steel multi-girder cross section. The total bridge length is 451’-6”. The existing bridge is 30 ft. from curb to curb and carries two lanes of vehicular traffic with 5 foot sidewalks on each side.

M&M provided engineering design review services for the replacement bascule bridge structural system.  The new bascule bridge progress set is a 200’-0” double leaf rolling bascule. The cross section includes 2 steel girders, floorbeams, and stringers. The floorsystem is composite with the filled grid deck. There is an underdeck counterweight and the structure is supported by large, reinforced concrete piers. 

The goal of the project was to ensure that the new structure is reliable, constructible and maintainable.

Bridge Geometry
Length of Main Span 150 ft
Total Project Length 451 feet
Lanes on Structure 2 lanes, 2 pedestrian sidewalks