I-10 Westbound, Twin Spans with an Approaching Rainstorm

Image by Ken Lund
The I-10 Twin Span Bridge, known locally as the Twin Spans, consists of two parallel trestle bridges. These parallel bridges cross the eastern end of Lake Pontchartrain in southern Louisiana from New Orleans, Louisiana to Slidell, Louisiana. The bridges were opened at a short ceremony on December 21, 1965 and are each constructed with 433 65-foot concrete segments.

Following the extensive damages from Hurricane Katrina, it was decided that the current Twin Spans were too vulnerable to storm surge and that the long term solution would be to construct two new spans. Ground was broken on July 13, 2006 on the project which will construct two new bridges 300 feet (91 m) east of the current spans. This 3 million project will construct two 3-lane bridges 30 feet (9.1 m) above the surface of Lake Ponchartrain, with an 80-foot (24 m) high rise near Slidell. Each span will be 60 feet (18 m) wide, consisting of three 12-foot (3.7 m) lanes, and 12-foot (3.7 m) shoulders on each side.

The wider bridges will eliminate the bottlenecking that currently occurs at both ends of the current bridges and also be able to accommodate 50 percent more traffic than the current twin spans, according to the Louisiana Department of Transportation and Development.

The new bridges will also have traffic cameras and electronic message boards to alert motorists of any potential problems on the bridge, much like the Lake Pontchartrain Causeway bridge.

The first new span opened to eastbound traffic on July 9, 2009 with the second span to follow in 2011. The old bridges will then be dismantled.

Construction Accident On October 30, 2008, as construction workers were preparing a form for a concrete pour, a girder collapsed sending 10 workers plunging into Lake Pontchartrain approximately 30 feet (9.1 m) below. One of the workers, Eric Troy Blackmon, who was tethered to the girder died in the accident.

en.wikipedia.org/wiki/Twin_Spans

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