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Récord: 6588 m
País: Estados Unidos
Localización: Apalachicola a isla St. George
Descripción:Features - September 2003
St. George Island Bridge
New Orleans-based Boh Bros. in final phases of constructing Florida's third-longest bridge
by Debra Wood
Boh Bros. Construction Co. of New Orleans is entering the final phases of construction on the new, $73 million St. George Island replacement bridge, one of the Florida Department of Transportation's first and largest design-build bridge projects.
There have been changes in the original contract, but "for the most part we're on budget and on time," said John Kemp, senior project engineer for construction engineering and inspection consultant Parsons Brinckerhoff Construction Services of Eastpoint, Fla.
Changes were made to the bridge's post-tensioning system after FDOT found corrosion from salt water on post-tensioning tendons on older state bridges.
The St. George Island Bridge crosses environmentally sensitive Apalachicola Bay, a mix of salt and fresh water, with a 72-ft.-high hump over the navigation channel. "It's the third-longest bridge in the state of Florida," said Scott Gros, project manager for Boh Bros. "And we have the longest post-tensioned, spliced-girder span in Florida. That five-span unit is nearly 1,200 ft. long."
Kemp said it's one of the longest post-tensioned, haunch-girder bridges in the United States. Crews began erecting haunch girders May 28. Three of the piers were set by the end of June, and all were in place by July 3. In August, after all five spans are set, workers will run post-tension tendons through 3 1/2-in. conduits embedded in the concrete girders to make the five spans work as one unit.
Concrete girders were selected rather than steel to avoid extra maintenance in the harsh water environment. Bridge designer and engineer of record Jacobs Civil of Tampa and Jacksonville, Fla., specifically designed the girders for the St. George Island bridge project.
Gulf Coast Pre-Stress of Pass Christian, Miss., fabricated more than 700 girders. Seventy-eight-in. Florida Bulb T girders were used on the low-level sections of the bridge.
Gulf Coast also supplied the 650 spun-cast piles used for the bridge's foundation. Spun-cast piles offered strength and speed advantages. Crews drove sets of three 54-in. diameter piles at 125-ft. intervals as well as some clusters of four to 15 piles near the navigation channel at 140 to 257.5 ft. intervals.
Boh Bros. received notice to proceed in July 1999, began testing piles for the 4.1-mi.-long bridge in August 2000 and started pile driving in January of the following year. Construction should be complete in October, but the road will not open to traffic until November, to allow utilities time to relocate their lines and cables to the new structure as well as striping required to switch traffic.
Once the new bridge opens, the University of Florida, in conjunction with the FDOT and Federal Highway Administration, will assess the ability of the existing structure's water-line footings to withstand a direct hit from a barge.
The 4 mile (6.4 km) St. George Island Bridge (designated State Road 300 from end to end, plus approaches) was built in 2002 (completed in 2004) when the two original bridges (cut by an island in the middle) that led to St. George Island, a small resort town 10 miles (16 km) from Apalachicola, Florida were deemed unsafe due to their old age. The new bridge, by bypassing the middle island, became the 3rd longest bridge in Florida. The north end of SR 300 is at US 98 (SR 30) in Eastpoint. It was opened on February 27, 2004.
Inserción: 2013-12-18 14:41:11
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