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GMA Dave Trips: The Atchafalaya Basin Bridge

Modern Marvel Cuts Through America's Largest Swamp
Posted at 4:00 AM, Nov 26, 2021
and last updated 2021-11-26 05:00:43-05

Swamp land. Remote, forbidding, treacherous. The Atchafalaya Swamp. It's the largest wetland in the United States. For years it was a major barrier, isolating Acadiana from much of the state. Before the interstate, a trip to Baton Rouge could take three hours, perhaps over four hours to get to New Orleans.

As the interstate system was being developed in the 1950s and 60s, a cut, straight through the Atchafalaya was needed. To find a base for an interstate crossing took years of research. Samples were taken and engineers found there was over 90 feet of mud and muck before a more stable sand base where bridge piers could sit. It appears the bridge isn't really that high, but some of these piers go down over 140 feet!

Cleared Path Before the Bridge is Built

After clearing a 300 foot wide path and digging a canal, prefabricated parts of the bridge were shipped from Lake Pontchartrain, through the Industrial Canal in New Orleans, to the Mississippi. Then downstream to the entrance of the Intracoastal Waterway. The barges then moved westward, eventually to the Atchafalaya River. Four days and 250 water miles to the job site.

Barge Entering the Intracoastal Waterway

After the piers are drilled down, the caps that would hold the roadway are placed by a barge crane with a 300 ton capacity. The caps were set to a precise line and grade within 1/16 of an inch.

I-10 Atchafalaya Bridge Being Built

Each prefabricated section of deck bed, which holds the roadway weighs 265 tons, and would slowly be hoisted onto the caps. They're then connected with reinforced steel and concrete. About 350 feet of roadway was completed per day, and it was opened to the public in 1973, dropping the drive to Baton Rouge to about an hour, and New Orleans in two.

Interstate 10 Eastbound Near Butte LaRose

Today, the bridge, also known as the Louisiana Airborne Memorial Bridge, carries over thirty thousand vehicles every day. The amount of products and materials moving east and west along I-10 is staggering. It also connects several ports along the Gulf coast. As efficient as the basin bridge is, it also has it's bad days. Since 2014, well over 1000 crashes have happened on the basin bridge, stranding drivers. Sometimes weather doesn't make it easy either. The ice storm and freeze earlier this year closed the bridge for days.

Frozen Roadway on I-10 East

But still a modern marvel. At just over 18 miles, it's the third longest bridge in the USA. only the Lake Pontchartrain and the Manchac Swamp bridges are longer. And as more of the widening project leading up to the bridge is completed, traffic should move more efficiently through the area. Which could mean more growth and economic development for Acadiana.

Don't forget to see the Atchafalaya National Heritage Visitor's Center at Exit #121 at Butte LaRose. If you want to see the original video "Swamp Expressway" uploaded by the Louisiana Transportation Research Center, click HERE.