Angelle Bergeron New crossing replaces one downed by Hurricane Katrina in 2005.

The joint venture contractor facing a Nov. 1 deadline to open two lanes of traffic on a replacement bridge for Mississippi's U.S. 90 over Biloxi Bay is well ahead of schedule, and glad of it, too. As the 2007 hurricane season begins to turn mean, the job is entering a phase less vulnerable to storm damage.

In Mexico, Hurricane Dean smashed into the Yucatan Peninsula on Aug. 21 with 145 mph winds. In Biloxi, crews were finishing the bridge's final column footing pours, which will protect the last of the 1,219 piles of the $342-million bridge if a storm roars in, as well as the contractor's lead on the schedule.

Angelle Bergeron With 21 cranes on the job, crews are cranking.

"I don't know of any other bridge built this fast from the date of the notice to proceed," says Steve Underwood, project manager for design–build contractor GC Constructors, a joint venture of Massman Construction Co., Kansas City, Mo., with Kiewit Southern Co., Fort Worth, Texas, and Traylor Bros. Inc., Evansville, Ind. It received notice to proceed from the Mississippi Dept. of Transportation on June 15, 2006. The bridge replaces one destroyed by Hurricane Katrina in 2005. Crews drove the first permanent pile less than three months after the start date. By Aug. 16 they were 64% of the way to delivering all six lanes, which aren't due until April 16, 2008.

"It's going to be kind of hard to build another bridge slower after this," Underwood says. "The owners know that too."

UNDERWOOD

Several factors are speeding the work, including a fast start–up aided by the presence of participating firms and equipment on the storm–ravaged Gulf Coast when MDOT gave the green light.

"We were on the jobsite before June 16, so when we got the notice to proceed, geotech work began immediately," Underwood says. "The owner was extremely cooperative with our getting started, and we had very good turnaround time on all the design work." Chicago–based Parsons Transportation Group is engineer. "Everybody from MDOT to contractors was on the job with the same idea: to get it done on time," Underwood says.

Related Links: Biloxi Bridge Gets Leg Up On 2007 Hurricane Season, August 20, 2006 Multimedia: Biloxi Bridge

The crossing consists of twin structures, each multispan precast concrete girders placed on poured columns. The JV was originally asked to deliver two lanes, as well as a land–based overpass bridge for a nearby railroad, by Nov. 13. "The contractor could see that production rates would allow for an earlier date for the two–lane opening and offered an alternative—Nov. 1," says Layla Essary, an MDOT spokeswoman. "They felt it was attainable."

The contractor is taking advantage of progress on the westbound structure to speed work on the eastbound one, working four cranes from westbound decks in addition to 17 cranes on the water. "He's pretty much got an assembly–line operation," says Kelly Castleberry, MDOT district engineer.

The new bridge has three primary differences from the bridge it replaces; greater height, shear keys and longer girders, Castleberry says. Most of the 1.2–mile–long crossing is constructed at elevation of 28 ft, up from its predecessor's 21 ft, and rises to 95 ft at the main navigational channel. The 120–ft–long spans are more than twice the length of the old bridge's and will be locked in place by shear keys 1 ft to 1.5 ft high.