Construction began in New Orleans yesterday on a £436M road bridge to replace a viaduct badly during Hurricane Katrina.
The 8.6km Interstate 10 Bridge, which crosses Lake Pontchartrain to link the US states of Louisiana and Mississippi, lost 64 of its 866 spans in the massive storm surge which swept across the lake (NCE 8 September 2005).Its replacement will be built on its eastern side at a higher elevation (9m above water) than its predecessor (3m) and user a denser concrete.One section of the bridge will rise to 24m to allow clearance for tall ships.'You're just not going to get storm surges that will reach that high,' said a Louisiana Department of Transportation and Development spokesman. 'The segments are much higher, longer, wider and denser than on the current bridge.'Those segments washed away during Katrina weighed between 260 and 300 tonnes, compared to the 800 to 1000 tonnes weight of each segment on the new bridge.Designed by Louisiana Department of Transportation and Development engineers in just eight months, the new bridge's deck will lock into its supporting piers.Unlike its predecessor, where the deck simply sat on top of its supports, this bridge's piers will have saddle-style caps.This will see the deck base slot into the piers, further reducing the risk of segments being washed away.The bridge will have a 100 year design life and is being built by New Orleans contractor Boh Bros.It is expected to take five years to complete and is the most expensive public infrastructure project in Louisiana's history, paid for by the US Federal Government.Until it is completed commuters to New Orleans will use its predecessor, which was repaired and fully reopened in January.