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: In-Service Engineering Inspection. Engineering inspection of substructure and superstructure using electronic data collection tablets, limited invasive inspection of selected post-tensioning (2005), development of Bridge Inspection Report with recommendations for future maintenance, project document organization and electronic storage, updates to the original Maintenance Manual developed in 1987, and Project Scoping Report (by their subconsultant Great Lakes Engineering).