U.S. Route 90 is one of the South's most traveled scenic highways. But more importantly, it's a major Gulf Coast artery, carrying travelers from the Florida Panhandle to New Orleans and beyond. So when Hurricane Katrina destroyed the existing four-lane bridge between Biloxi and Ocean Springs in 2005, the Mississippi Department of Transportation (MDOT) knew the structure had to be rebuilt as quickly and durably as possible.
To expedite the project's completion, MDOT engaged the services of an ocean engineering firm, OEA Inc. The consultant developed a computer model which enables design engineers to predict the storm surge plus maximum wave height. Engineers used this information to ensure they provided sufficient elevation for the new bridge to clear water levels expected from another catastrophic hurricane.
With this information in hand, the agency advertised and subsequently awarded the $338 million design-build contract to GC Constructors, a joint venture of Massman Construction Co., Kansas City, Mo., Traylor Bros. Inc., Evansville, Ind., and Kiewit Southern Co., Fort Worth, Texas. The joint venture contracted Standard Concrete Products of Columbus, Ga., to supply the prestressed concrete beams the project would require.
The new bridge is the area's focal point. It provides the highest point above the navigation channel. The 1.66-mile-long bridge rises 95 feet above Biloxi Bay. The span affords unobstructed views to travelers while allowing large ships to pass under it without lowering their masts. Constructed as two, side-by-side, high-rise superstructures, the bridge carries six lanes of traffic and a shared 12-foot-wide path for bikers and pedestrians. The project also included twin 800-foot-long bridges over a railroad in Ocean Springs.
Beating the schedule
Once MDOT awarded the project in June 2006, it proceeded at a torrid pace. The north lanes for westbound traffic opened 16 months later and 12 days ahead of schedule. At its peak, the project team employed 450 people and required 18 floating cranes.
The production team at Standard Concrete aided in this success. “Two major factors contributed to the speed with which we were able to complete our portion of the project,” says Peter Pieterse, plant engineeer for Standard Concrete Products' facility in Mobile, Ala. “MDOT engineers accepted our recommendation to use self-consolidating concrete (SCC) to cast the beams. And we used a debonded, rather than draped, strand design for the prestress cables, which allowed faster production of the beams so we could inventory them for delivery as needed.”