Crews are working around the clock to rebuild a 120-year-old stone wall that collapsed and took part of Route 209 with it, closing the highway in Nesquehoning Borough for an estimated six to eight weeks.

The wall gave way Saturday, undermining the roadway and sending rock and trees down the slope toward the Lehigh River. The slide also forced the closure of the Reading & Northern Railroad line below.

“A stone wall that was built 120 years ago gave way and collapsed, and resulted in the roadway collapsing with it, with a whole slew of rocks and trees going down towards the Lehigh River,” state Transportation Secretary Mike Carroll said in a social media update Monday.

The Pennsylvania Department of Transportation mobilized its own personnel and several contractors to size up the damage and draw up a repair plan. J.D. Eckman Inc. of Atglen is the prime contractor. Equipment reached the site and work began Sunday morning.

“We’ve employed an emergency contractor to reestablish the wall to repair the road. We’re going to work 24/7 until we get this done,” Carroll said.

The job includes stabilizing what is left of the wall, hauling away the fallen rock, rebuilding the collapsed section and repairing the road, PennDOT said in a news release. The railroad line is expected to reopen before the highway does. The agency cautioned that all time frames are estimates and subject to change.

“We’re probably looking at about six to eight weeks before we can reopen 209. We’re going to work like heck to make sure we get it done quicker, and we’re going to keep updating the community as this process unfolds over the next couple of weeks,” Carroll said.

The compromised stretch of road runs an estimated 50 to 100 feet, said Sean Brown, press officer for PennDOT Engineering District 5. From the road down to the rail line is roughly 260 feet.

“The rock wall that holds up the road collapsed, and that undermining compromised the roadway,” Brown said.

Route 209 is closed between Route 903 and Route 93. The posted detour uses Route 443, Route 309 and Route 209.

In Jim Thorpe, police are watching to see whether the closure pushes heavy trucks onto borough streets.

“Tractor trailers are not permitted up on Center Avenue. The state put signage up a few years ago, not permitting tractor trailers up in that area,” Police Chief Joe Schatz said.

Schatz said he had been waiting to meet with PennDOT because the collapse happened over the weekend.

“I would just caution people to follow the signs that are posted for that area,” Schatz said. “We’re going to play it by ear, see what happens. If we’re seeing an influx of larger vehicles, we may end up talking to PennDOT to see what other parameters we can put in place until this project is done.”

The slide has also rerouted one of the area’s biggest fall tourist draws. Reading & Northern has temporarily moved its Lehigh Gorge Scenic Railway excursions to Nesquehoning, because the slide struck the railroad tracks west of Jim Thorpe, the company said in a news release.

Trains now leave the station at 1 Iron Horse Way and head east into Lehigh Gorge State Park, rather than west out of Jim Thorpe. Departures are at 11 a.m., 1 p.m. and 3 p.m. Riders get a 70-minute trip instead of the 45-minute ride normally offered in the fall. Parking is free.

The schedule is set to run through Sunday, Nov. 8. The railroad said it is monitoring the repair work closely and will update the schedule as developments warrant. Details on the remaining fall excursions out of Pottsville, Pittston and Reading are expected later this week.

The railroad has posted driving directions at www.lgsry.com for guests coming from Jim Thorpe, routing them around the closed stretch of Route 209. The Black Diamond Company Store at the Nesquehoning station is open every day trains leave from there.