Rigolets Pass Bridge Geotechnical Investigation
The team overcame technical and logistical challenges to complete geotechnical testing for this major design-build project.
The Louisiana Department of Transportation and Development (LA DOTD) contracted with GeoEngineers’ Baton Rouge office to complete a geotechnical investigation, including borings and laboratory testing, for the new Rigolets Pass Bridge and approaches on US 90 outside New Orleans, Louisiana. The $50 million high-rise bridge is a little more than one mile long and has no overhead trusses. The bridge reaches 72 feet at its highest point and allows marine vessels to travel underneath it, unlike the bridge it replaced.
GeoEngineers completed its part of the project in less time than had originally been scheduled, thanks to extra effort and hours put in by the project team, who were housed on the testing barge for the duration of the project.
The bridge, which connects eastern New Orleans with southeastern St. Tammany Parish, runs over a very crowded utility corridor that provides major communication and fiber optic cables to New Orleans. This presented a challenge to the GeoEngineers team as they conducted their borings, because the more commonly used floating barge (secured by a series of anchors dropped from the waterline) posed too much risk for damage to the utility cables. GeoEngineers instead used an elevated barge with four static legs, placed carefully around the cables, and deck that raised or lowered as weather permitted.
The bridge opened to motorists in January 2008.
- GeoEngineers used truck-mounted rotary drills on an elevated barge to avoid disturbing the utility corridor running in the waterway under the bridge and to limit the possibility of snagging a cable with an anchor from a floating barge.
- The project team used divers and surveying equipment to ensure they were drilling in the exact locations specified so as to avoid damage to the cables.
- The elevated barge could raise and lower its deck as needed to allow the GeoEngineers team to work during windy weather and in choppy waters.
- Completed borings in up to 40 feet of water and up to 340 feet in depth below the mudline
- GeoEngineers staff worked shifts of more than 12 hours to minimize costs associated with the drilling operation.