When traffic flows on all six lanes of the new $803-million Interstate-10 Twin Spans in New Orleans this September, the region that was devastated by Hurricane Katrina in 2005 will receive a much-needed symbol of recovery.
While relief can't come soon enough for area residents, the Twin Spans' build team worked diligently to fast track the project, which is scheduled to open almost a year ahead of schedule.
The bridge connects east-west I-10 traffic over Lake Pontchartrain. Katrina's 30-ft storm surge on Aug. 29, 2005, tore apart the 1960s-era crossing with uplift and wind, bashing decks off 58 segments and misaligning 473 others. About 40% of the structure was destroyed.
Up and over
Fully funded by the Federal Highway Administration, the new bridge is 300 ft south of the old one. At 30 ft high, the low deck will be 21 ft higher than the original. The bridge meets ship impact standards of the American Association of State Highway and Transportation Officials. It incorporates larger foundations, more redundant pilings and more reinforcement to engage the piles with the caps, making them more resilient to lateral impact, says Arthur D'Andrea, project manager for the Louisiana Dept. of Transportation and Development (DOTD).
The hurricane-resilient 100-year bridge was built with higher-performance, high-strength (10,000-psi) concrete that is very resistant to saltwater corrosion and wind and water loads. Lower-level connections between super- and sub-structure are strong. Beams are connected by means of dowels placed at angles to the cap to resist uplift. Shear keys have been added to restrain the girders against lateral displacement. Each of the 60-ft-wide spans will feature three 12-ft-wide lanes of traffic with two 12-ft-wide shoulders.
When the spans open this fall, Boh Bros. Construction, New Orleans, will have completed its $379-million contract to construct two 4.5-mile-long, low-level runs of the east-west artery well ahead of schedule. TKM, a joint venture of Traylor Bros., Evansville, Ind., Kiewit Southern, Atlanta, and Massman Construction, Kansas City, Mo., completed its $171-million contract 178 days early. It constructed the “hump,” which is made up of 200-ft-wide by 80-ft-high spans that cross a shipping channel.
“It's a real repetitive structure, so we were able to fine-tune work practices to be more efficient,” says G.J. Schexnayder, Boh's project manager. Skylar Lee, project manager for the TKM joint venture, agrees that the bridge was “typical construction on both the approach and high-level main span,” which contributed to the fast pace of the project and made the tie-in between the two projects proceed smoothly.
Improving the request for information process was key to speeding progress, Schexnayder says. “On the repair job, no one had time [to wait for responses]," he says. "Everyone had guys who could make decisions in the field 24 hours a day. Our design engineer on site, Dennis Gowins with HNTB, would design and get approvals right away.” Schexnayder points out that “it didn't feel like we were working for an owner. It felt like everybody was on the same team.”