FAIRLEE — An upcoming ledge repair project will close a 6-mile stretch of Interstate 91 South between Bradford and Fairlee, likely through the summer. 

Scheduled to begin within the next two weeks, the project will stabilize the rock face that towers over the interstate, an area known as the Palisades, Vermont Agency of Transportation Project Manager Bruce Martin said Wednesday.

Southbound traffic will be diverted onto Route 5 during the closure, Martin said. 

“This is a very large and significant undertaking,” Martin said of the upcoming project, for which the total cost has not yet been determined. The scope of the work is still being finalized, he said.

The metal mesh curtain that covers the rock face was installed in the late 1990s and is at the end of its useful life, he said. 

Loose material and unstable sections of rock will be removed by workers rappelling down the cliff face and using tools including air bags that are thin enough to fit into cracks and powerful enough to dislodge unstable rock when inflated.

The cliff face rises more than 500 feet above the roadway, creating the potential for debris to fall onto the northbound lanes during the rock work. To avoid endangering drivers, rolling roadblocks will be used in the northbound lanes throughout the project, Martin said. 

In late February, the same stretch of the southbound I-91 was closed for more than two weeks when rocks and debris broke loose and fell onto the highway. Traffic was diverted to Route 5 between exits 15 and 16.

The left lane of I-91 South opened to traffic on March 13, but the right lane remains closed. 

The longer duration of the upcoming Route 5 detour will be inconvenient for Fairlee residents and for drivers diverted by the construction, Fairlee Police Chief Wayne Briggs said Thursday.

“People were very courteous driving through the village,” during last month’s detour, he said. But “there were complaints about speeding on the straightaways.”

The upcoming detour will coincide with haying and seeding projects on the agricultural properties along Route 5 north of Fairlee, and the presence of farm equipment on the road will likely slow traffic, Briggs said. 

A temporary stoplight will be installed at the intersection of Bridge Street and Route 5 to assist with traffic control. 

While his department is prepared for the increased traffic volume, “you’re always worried about the what ifs,” Briggs said. 

The Fairlee Palisades have been closed to hiking and climbing this spring to protect nesting peregrine falcons, so the Vermont Fish and Wildlife Department is working with VTrans to make sure that the project does not disturb the birds.

The nesting area is tucked in a cove about one-third of a mile south of the work site, which should be far enough away to avoid impacting the nests, Vermont Fish and Wildlife Department nongame bird biologist Jillian Kilborn said Thursday. 

The workers will likely be out of sight of the peregrines, and “if the birds can’t see, they might not mind at all,” Kilborn said. 

Christina Dolan can be reached at cdolan@vnews.com or 603-727-3208.