A landmark of New Orleans, the I-10 Twin Span Bridge, (known as the Twin Spans) are two parallel bridges that cross Lake Pontchartrain from New Orleans to Slidell.
After Hurricane Katrina in 2005, the Twin Spans suffered extensive damage. Though the bridge was repaired after the storm, it was decided a long-term solution would be to construct two new spans.
Construction of the new bridge began in June 2006 and is the largest public works project in Louisiana history.
Taller, wider and built with enhanced materials and construction techniques, the new bridge, which will cost $800 million, is being built 300 ft. (91.4 m) east of the current spans. The new spans are being built 21 ft. (6.4 m) higher to protect against high storm surge. Once the new bridge is completed, the current bridge will be demolished.
The first new span opened to two lanes of eastbound traffic in the summer of 2009. The westbound span is scheduled to follow suit in mid- to-late 2011.
“The magnitude and complexity of this bridge replacement project is readily evident,” said Steve Heraty, deputy project engineer of CEI from Volkert Construction Services, the construction engineering and inspection consultant for the project.
“However, this bridge is much more than concrete, steel, manpower and equipment. It is a visible reminder of the devastation of Hurricane Katrina and the recovery of the region in the aftermath of the hurricane.”
The new bridge features an 80-ft. (24.3 m) high-rise section to provide vertical clearance for marine traffic. The two parallel structures, each will be 5.5 mi. (8.8 km) long. Both bridges will be 60 ft. (18.2 m) wide and accommodate three 12-ft. (3.6 m) travel lanes.
The project is being funded by federal tax dollars from the Federal Highway Administration and The Louisiana Department of Transportation and Development (LaDOTD) is administering the project.
Boh Bros. Construction Co. is the main construction company on site and is building the level portion of the new bridges and the approaches. This work (a $375 million portion of the project) includes pile driving, placing pile caps, placing girders laying the roadway decks and pouring retraining walls. TKM Joint Venture is the construction contractor for the high-rise navigational section of the new bridges. Volkert Construction Services is the construction engineering and inspection consultant for LaDOTD. Right now the workers aren’t working shifts, though Boh Bros. does begin the workday at 1 a.m. when concrete pours are slated.
According to Volkert Construction Services, included in the design are shear keys and reinforced steel and concrete tie-ins between the bridge decks and caps that will help prevent misalignment and toppling due to storm surge. The entire bridge also is being constructed using high-performance concrete that is stronger, denser and less porous than normal concrete. The concrete also is more resistant to salt water corrosion.
The equipment being used for the project is typical for a major bridge construction effort. It includes cranes, barges, tugboats and screeds used for pouring concrete.
“There’s a lot of it and working conditions on Lake Pontchartrain can be crowded at times,” added Heraty.
As to the history behind the spans, the bridge opened in 1965. LaDODT reconstructed the spans in 2005 after being damaged by Katrina. As part of the $30.9 million project (Boh Brothers were the contractors) both bridges were worked on and completely reopened the following year.
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