DOTD, at this time, has no concerns related to the integrity of La. 70 in Assumption Parish. However, out of an abundance of caution, DOTD is currently conducting daily visual roadway inspections, weekly bridge inspections, and monthly GPS surveys of LA 70 and area bridges.
We are coordinating daily traffic control and signage, providing aerial photography as requested, and have developed a traffic contingency plan for LA 70.
Publications and Data
In light of the most recent developments involving a second cavern located closer to LA 70, DOTD has enacted plans for enhanced and automated, continuous monitoring of LA 70 and the three area bridges (Bayou Corne, Grand Bayou and Bayou Choupique) for movement and subsidence. These enhancements include the installation of tilt and accelerometer sensors on all three bridges, and Shaped-Accelerometer Arrays (SAA) located between the LA 70 right-of-way and the sinkhole, and at the two closest bridge locations to measure movement. (120 feet in length; measure vertically and horizontally)
Four Continuously Operating GPS Reference Stations (CORS) were installed in the area for automated, continuous monitoring of subsidence. One is located near the roadway, two are located near the closest bridges, and one location is yet to be determined. (LSU conducting, higher accuracy, measuring with regional geographic perspective)
Additionally, DOTD is developing a detection and motorist warning system, which will use data from the monitoring systems and alert responders. Monitoring system will connect to DOTD’s Traffic Management Center in Baton Rouge. Notification process is in development.
DOTD is conducting a feasibility study to determine if an alternate route could be built in the affected area in the event that La. 70 is compromised and help identify possible the cost. The study is expected to take 6 months. During this time, DOTD will hold public meetings to provide information about the proposed options.
For additional questions or comments, or to sign up to receive e-mail updates, contact DOTD’s Customer Service Center at 1-877-4LA-DOTD (1-877-452-3683) or e-mail Customer Service. The center is open 7:30 a.m. – 5 p.m., Monday through Friday.
Cursory Bridge Inspections are conducted weekly on all three bridges in the footprint of the salt dome: the Grand Bayou Bridge, the Bayou Corne Bridge, and the Bayou Choupiqué Bridge.
These inspections include taking profile checks on all bents on both sides of the bridge, a visual inspection underneath each bridge by boat and/or foot, and streambed profile measurements at each bent. No movement has been detected in the bridge or the streambed. These weekly inspections are conducted on Friday or Saturday. Inspections began the second week in August and will continue until further notice.
Profile checks are compared to the original reading found on the first field visit, which was conducted on August 11. Attached are the comparative graphs, as well as copies of the cursory bridge inspection reports. No abnormalities have been found.
Bayou Corne FAQs
What kind of monitoring is being done to make sure the roads are safe to drive on?
The Department of Transportation and Development continues to monitor the roads in the area and, at this time, has no concerns related to the integrity of its state roads, specifically La. 70 in Assumption Parish. DOTD would like to remind motorists to practice caution while driving on La. 70 in Assumption Parish, as there may be heavy truck traffic entering and exiting the roadway.
Out of an abundance of caution, DOTD engineers are continuously monitoring the state road system in this area. If conditions change, DOTD crews are prepared to close roads immediately to ensure public safety and will announce appropriate detours. DOTD engineers are measuring elevation levels monthly using GPS technology at four locations along La. 70 - one on Highway 70 perpendicular to the site, and at the Bayou Choupique, Grand Bayou and Bayou Corne bridges. So far, no changes in elevation have been found at these locations.
Has DOTD put together a plan to reroute La. 70 if it would be closed? What is the plan for where the detour would occur?
DOTD, at this time, has no concerns related to the integrity of its state roads, specifically La. 70 in Assumption Parish. However, out of an abundance of caution, DOTD engineers are continuously monitoring the state road system in this area -- 24 hours a day with roving patrols and frequent surveys. If conditions change, DOTD crews are prepared to close the roads immediately to ensure public safety and will announce appropriate detours.
DOTD is monitoring LA 70 from the Bayou Corne Bridge east to LA 996. The Department is also monitoring a one-half mile stretch of LA 69 from its intersection with LA 70.
In the event conditions develop that would make the road network unusable or unsafe, we have planned the detour to be as follows:
- Traffic traveling to Pierre Part and points south will be directed to LA 1 South to LA 398 West, to LA 662 West, to Hwy 90 West to LA 70.
- Traffic traveling from Pierre Part and points south will be directed to US 90 East to LA 662 East, to LA 398 East, to LA 1 north to LA 70.
- Local traffic (passenger vehicles and trucks below the posting of the Bayou Pigeon Bridge (15/25)) will be able to take LA 997 to LA 75 to LA 404 to LA 69.
If the order is given to close the road, DOTD crews will install trailblazing signs to notify drivers of the detour. We will also install Variable Message Signs (VMS) at LA 70 at LA 1 and LA 70 at LA 69. We will notify District 03 and they will install a VMS on LA 70 just north of Morgan City.
Link to Environmental Documents: LA 70 Environmental Assessments