Design-Build Accelerates Completion
South Mississippi along the Gulf Coast is an area with only two east-west corridors, U.S. 90 and I-10. Nearly 40,000 cars traveled across the Biloxi-Ocean Springs bridge daily, before the hurricanes. That traffic is now being routed to I-10, which can cause time delays for commuters, as well as congestion on the main thoroughfare.
Building two new bridges as quickly as possible became a major consideration when choosing design-build as the delivery method for both the Bay St. Louis and the Biloxi-Ocean Springs bridges over U.S. 90. "Time is of the essence on this project," says Kelly R. Castleberry, P.E., District 6 area engineer. "Design-build was the fastest way to get this bridge constructed and back up for the public."
A pilot design-build project for a rural bridge in district 5 had been planned as MDOT's foray into design-build. The need for quick delivery of two new bridges on the Gulf Coast usurped the District 5 project, making the Bay St. Louis bridge and the Biloxi-Ocean Springs bridge the first design-build projects for the department.
Castleberry says the normal timeframe for a project of this magnitude in the design-bid-build process would take around five years, with around 18 months for design and three-and-a-half years to build.
Work began in June on the $338.6-million Biloxi Bay Bridge. The design-build project for reconstructing the Biloxi-Ocean Springs bridge will have its first milestone in November 2007, when two lanes are open for traffic. The entire project is only 18 months long, with a completion date is April 16, 2008, a considerable time savings for MDOT.
GC Constructors, a joint venture of the firms Massman Construction Company, Kansas City, Missouri; Kiewit Southern Company, Peachtree City, Georgia; and Traylor Brothers, Inc.; Evansville, Indiana, won the bid, and is performing the work.
When asked about cost savings with design-build, Castleberry couldn't be certain, but said he thought there were user cost savings associated with the project. "The cost for people to take this detour from Biloxi to Ocean Springs daily is pretty significant, in the amount of delay for people taking alternate routes to get to work or to get home, the amount of time that they're waiting for traffic, and the amount of time that they're burning fuel in their cars," says Castleberry. A quick reopening of the bridges along U.S. 90 would certainly help curb these costs.
The new bridge will be one mile long and have a clearance of 95 feet from the water's surface, eliminating the need for a drawbridge for marine navigation. It will have three lanes in each direction, safety shoulders and a multipurpose pedestrian pathway on the south side. A short wall will separate pedestrians from traffic lanes, and there will also be a railing with some aesthetic features.
The new bridge will be around 120 feet south of the old bridge. The contractor completed demolition of six spans of the old bridge on each end in September. The remainder of the bridge will be demolished as the new bridge is built. GC Constructors is using WC Fore Trucking to demolish the old bridge and dredge the work channel.
All materials for the old bridge are being used to build a new reef just south of Deer Island. Says Castleberry, "The Department of Marine Resources (DMR) went out and flagged areas south of Deer Island to help protect the island from future storms."
TL Wallace Construction of Columbia, Miss., has been subcontracted to do much of the land work, including demolishing and rebuilding two railroad overpasses on the Ocean Springs side, and the road abutments on the Biloxi and Ocean Springs.
To reduce settlements where the abutments will be placed, TL Wallace is building a 20-foot to 25-foot earthen surcharge on each side. The shear weight of the soil placed on top of a settlement plate will help compress and squeeze out the water from the pores. We're doing it on both sides of the bridge. Right now they're doing the Biloxi side, and they're gearing up to start the Ocean Springs side. "A good clay soil with a little sand is being used for the surcharge," says Castleberry. "Its weight will consolidate and squeeze out any water, through the wick drains that have been installed."
The process will take anywhere from three to six months. Once settlement has stopped, the soil will be removed and construction on the abutments can begin.
Original railroad overpasses that are being demolished on the Ocean Springs side had only four lanes. The rebuilt railroad overpasses will have six lanes, to prevent a bottleneck in traffic from the main bridge. Though the railroad bridge and the main bridge are two separate structures, when complete, they will look like one bridge.
GC began pile driving operations around mid September. "We've basically completed our pile program and we've started permanent pile installation," says Steve Underwood, project director for GC Constructors. "We've also started permanent footing and column installation at this point." Underwood says his crew is driving pile 80 feet to 115 feet on the west side and also the high-rise section of the main span, using mostly Manitowoc Cranes ranging from a 3900 up to a 7000, and Conmaco air hammers.
The bridge will have 72 bents, with the low level and part of the high rise constructed with eight piles per bent, working up to 28 piles per bent in the main portion.
Underwood says that he is not having problems attracting enough labor, but that may change as the project progresses. "We're far from our peak employment right now," says Underwood, adding that the project is currently employing 150, but will peak at over 300 in February or March. Crews are currently working 10-hour shifts six days a week. Underwood says that possible labor shortages in the future could be attributed to more than the 2005 hurricane season. "Generally on the Gulf Coast, from Florida to Louisiana, there's a shortage of qualified help, and it's very difficult to say that we'd experience a shortage from the last hurricane season because there was so much going on in the Gulf before the hurricanes."