The DOT announced on March 6 that the portion of state Route 73 will operate with a single lane of traffic until approximately March 27. The closure could extend if the weather over the next few weeks does not permit roadwork.

“It’s an emergency repair, so it’s hard to know exactly what it’s going to take to complete the work,” said Keene town Supervisor Joe Pete Wilson Jr. “As long as it’s done in the next few weeks before the (April 8) eclipse, I don’t think it’ll be much of an issue.”

The roadwork will repair the slope above the road, which sits against the southbound lane, while the northbound lane will operate with alternating traffic directed by temporary traffic lights on either side.

Wilson said that unstable slopes above roadways have been a recurring problem this winter in Keene.

“Rockfall has been a real issue this winter with such a strong cycle of freezing and thawing we’re experiencing here in Keene on some of our roads, on county roads,” he said.

Wilson said that he did not know who alerted the DOT of the unstable slope above state Route 73, but most Keene residents are vigilant about unstable slopes because of their prevalence in the area. He said that there have been “rocks getting spit out” onto roadways from slopes near Cascade mountain, Hurricane Road, Otoole Road and on state Route 9N leading from Keene to Upper Jay.

“This weather has really made it an issue, so everybody’s looking out for it and keeping an eye on areas of concern,” he said.

Paul Smith’s College natural science professor Dr. Curt Stager said rock slides are a naturally occurring phenomenon that are exacerbated by wintry conditions.

“Gravity still works, and after a winter, it works even better,” he said.

In the winter, freezes break rocks loose from rock faces and also lift rocks out of soil in which they’re embedded. Melts will trigger slides.

“(Rock slides) can be a problem anytime it’s not frozen,” Stager said. “If you look at a gravel face or some other place that isn’t covered with vegetation, you’ll see a cobble, a pebble, a boulder lifted up by frost from the dirt.”

When a melt happens, the rocks are free to tumble down the slope, becoming a particular problem if the slopes are steep. The added water from melts and rainfall help lubricate the slope, aiding the rocks on their way down to the road.

“It’s sort of a double whammy,” Stager said.

Stager said that the Keene area is more susceptible to landslides because of lake sediments from the Ice Age in the soil.

“That valley does have extra slippery sediments because there was a glacial lake there,” he said. “If the mud at the bottom of the lake was very fine-grained, then when it gets wet, it slides more easily than a combination of coarse rocks and pebbles and sand and things like that.

He’s also read historical reports of rock slides near that stretch of state Route 73, and said that this latest closure is a product of historical patterns and an unusual winter.

“This winter revives an ongoing chronic problem along that stretch of road that dates back before the pavement because it is so steep and it’s an exposed slope that’s eroding,” he said. “You’re always going to have to be working on it.”