October 21, 2008 -- The Michigan Department of Transportation (MDOT) today completed repair work on the Zilwaukee Bridge over the Saginaw River, in Saginaw County. The repairs involve placement of a retrofit - - a post-tensioned, steel-bracing system around the exterior of a damaged bridge beam. North- and southbound I-75 lanes across the bridge now are fully open to traffic. The posted detour to I-675 northbound lanes is no longer in effect. Work was completed today, Tuesday, Oct. 21.
With the assistance of MDOT's structural research experts from Lansing, diagnostic load testing was completed on the bridge before the closed lanes reopened. Crews attached strain gauges to the concrete, after the retrofit had been placed in several locations. The bridge then gradually was loaded with heavy trucks, and readings on the strain gauges were taken every two seconds. These readings were compared to the expected performance of the retrofit to ensure that it is working properly.
"The retrofit is a permanent fix and MDOT engineers expect it will provide a durable and safe re-enforcement for the damaged bridge joint," said Bay Region Engineer Tony Kratofil.
MDOT will conduct ongoing inspections and testing to assure the safety and reliability of this structure.
"Although this process has taken longer than expected, our focus during the last eight months has been on determining the right fix and returning the bridge to safe operating condition as quickly as possible," said Kratofil.
In February 2008, MDOT was scheduled to complete the routine replacement of three-foot-diameter bridge bearings across the Zilwaukee Bridge. Near the onset of this project, the contractor, Midwest Bridge Company reported to the Michigan Department of Transportation (MDOT) that reinforcements within the bridge beams were discovered that were not expected. Upon opening a bridge joint, crews encountered and cut the reinforcement steel. These steel bars were reported by the contractor to be situated in a way that complicated installation of the new bearings.
In April 2008, MDOT consulted with the designer and determined that it was best to halt the project in order to come to a decision about how best to proceed. Work was immediately suspended. The determined fix was the retrofit concept.
The design consultant, Parsons Transportation Group, began preparing the design for the retrofit. In addition, MDOT hired a second consultant, Janssen & Spaans Engineering, to review the retrofit design and provide ongoing technical advice to MDOT during the fabrication and installation of the retrofit.
The fabricator, Wabash Steel, LLC, Vincennes, Ind., began fabrication of the bracing system on July 3, 2008. This work took approximately five weeks to complete. The contractor, Midwest Bridge Co., Williamston, Mich., started the installation process on Sept. 2, 2008. This work has taken approximately six weeks to complete.
The repairs are expected to cost approximately $1.5 million, which includes retrofit assembly, additional equipment, and crossover construction to maintain traffic on holiday weekends. This is being paid for out of the current contract funding. The awarded contract amount was for $3.3 million.
"MDOT is still assessing the cost for the repairs and will seek the services of an independent consultant to provide a thorough and objective analysis regarding responsibility for the cost of the repairs," Kratofil said.
Protect Michigan families: Where Workers Present Drive 45! - A message from MDOT and Michigan's Give 'em a Brake Safety Coalition
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