Ledge blasts for turnpike safety to last several weeks

Thursday, April 29, 2004
The Boston Globe
By Erica Noonan

MASSACHUSETTS TURNPIKE, MILE 101.5 — The Pike is eerily quiet beneath the towering ledge of gneissic granite on the Westborough-Upton line. Traffic is stopped in both directions. Explosive gel has been inserted into deep crevices in the rock face.

It’s 1 p.m. on a Thursday afternoon, and workers for McCourt Construction of Boston have exactly 15 minutes to blast away 475 cubic yards of rock on the eastbound lane, clear the mess off the road, and get cars moving again.

A warning siren sounds, and the workers preparing the blast scene quickly retreat.

The 15-minute countdown begins with a muffled boom. An avalanche of rock slides down 50 feet, covering much of the highway below. Two front-end loaders and an excavator plow through the acrid air, quickly sweeping up the boulders that rival a Volkswagen Beetle in size.

Men on foot rush around collecting smaller rocks that have landed scattershot around the median strip. They look like children scooping up candy at a parade.

By 1:10 p.m., State Police have two lanes of traffic moving again, although the commute will remain slow for much of the afternoon, as 18-wheeler trucks struggle to regain lost momentum on the hills near the junction of Interstate 495 and other motorists rubberneck to see what all the fuss was about.

The cleanup crews have made haste for good reason — they are contractually obliged to get traffic moving within 15 minutes, or they face a fine of $500 per minute. (The Pike isn’t kidding about this. In a 1997 blast project near Sturbridge, a contractor kept traffic stopped for an additional 45 minutes. He was charged $22,000.)

The blasting project at the Westborough-Upton line will go on at least until the end of May, eventually chipping away 25,000 cubic yards of granite, a rock face roughly four football fields long, a half-field high, and 20 feet deep. It will take more than 1,000 dump truck loads to haul it all away. Workers can only blast after the morning commute and before 2:30 p.m., and because preparations take several hours, they usually can only perform one blast per day, officials said.Eliminating falling rock before it falls isn’t the most glamorous highway improvement project, but the Pike is spending $10.6 million out of its operating budget to blast this ledge, build new, glare-reducing concrete barriers, and repave 5 miles of road. Nobody has been killed by falling rock since the highway opened in 1957, a good record considering much of it is carved out of rock.

Pike officials want to keep it that way.

A close call in 1994 — when a sudden midday rockslide buried an eastbound onramp in Auburn — was frightening enough. Panicked highway officials brought in sniffer dogs to determine whether there were cars and people trapped under the massive rock pile; it took hours to determine that there were not.

It was “pure chance” that no cars were passing under that well-traveled ledge of shale when it gave way, said Turnpike Division Engineer Ron Dionne.

“That was a cautionary tale of why you pay attention to rock,” he said.

Huge, 20-foot-long steel screws now anchor what’s left of the Auburn rock face to its base.

It’s not SUVs or tractor-trailers that are to blame for this new hazard. Decades of natural freeze-thaw cycles and the widening of the Pike from two to three lanes in the mid-1960s mean that the 88,000 or so vehicles that travel this stretch each day pass perilously close to hundreds of yards of weakened granite ledge.

The ongoing traffic delays at Mile 101.5 are inconvenient, Pike officials acknowledge. But the safety factor is worth it, said Pike operations director Mike Swanson.

“It was but for the grace of God that nobody got killed [in Auburn],” Swanson said. “We know it’s annoying to have to sit and wait. But just bear with us.”