The Zilwaukee Bridge carries I-75 over the Saginaw River near Saginaw, Michigan. The precast box girder structures provide for four 12′ lanes of traffic in each direction. Since opening to traffic in 1987 after a construction accident delayed construction for over 2 years, MDOT has required a detailed engineering inspection and evaluation to be performed every four years. The 8,000’ long bridge consists of two separate structures with span lengths from 130’ to 392’. Each structure is 73.5’ wide and varies in depth from 8’ to 20’. The 150’ tall cast-in-place piers are twin hollow box columns with a connecting strut near the top. The superstructure was built in balanced cantilever using either a self-launching over-head gantry or a ground-based crane.
Corven Engineering Role: Development and Proposal of Conceptual Bridge Jacking Alternatives, Design of Temporary Works to perform the Bearing Replacement. As part of Corven Engineering’s role, the Bearing Replacement Plan was modified to eliminate ground based falsework supports for the Pier Jacking procedures, eliminating the disturbance of classified hazardous fill material. With minor modifications and the installation of temporary brackets, the jacking procedure is performed from the top of the piers, saving time and money for the Contractor.