HARTFORD, Tenn. (AP) — Heavy rain, flooding and a rock slide have again closed a section of the major cross country highway Interstate 40 along its narrow corridor through the Great Smoky Mountains.

The slide and flood happened Wednesday afternoon around mile marker 450 in Tennessee, just to the west of the state line with North Carolina, the Tennessee Department of Transportation said on social media.

Crews continued to work Thursday to get the water and rock off the highway and had not released when they think the road could be reopened, the DOT said.

Engineers have found significant damage on both the highway and nearby ramps which was more extensive than originally thought, Republican Tennessee Rep. Jeremy Faison said on social media.

“Several areas remain under water, and there are potentially compromised slopes. Geotechnical engineers are on-site today to assess the stability of those slopes,” wrote Faison, who represents the area.

The damaged section is part of 12 miles (19 kilometers) of I-40 in North Carolina and Tennessee that was washed away or heavily damaged by flooding that roared through the Pigeon River gorge during Hurricane Helene in late September.

Crews repaired and shored up enough of the old highway to open one narrow lane in each direction in March.

The lanes are separated by a curb several inches high that had to be removed to let vehicles stuck by the flooding and rockslide to turn around and go the other way.

About 2.5 to 3.5 inches (63 mm to 89 mm) of rain fell in the area over about three hours, according to the National Weather Service.

The permanent fix to stabilize what’s left of the road will involve driving long steel rods into bedrock below the road, filling them with grout and spraying concrete on the cliff face to hold them in place. It will take years.

I-40 runs from Wilmington. North Carolina to Barstow, California, and any detour around the Great Smoky Mountain section is dozens of miles. Trucks have gotten stuck on twisty narrow mountain roads and are banned on another major highway through the area U.S. 441 through Great Smoky Mountains National Park.