Posted Monday, February 26, 2001
By Doug O'Harra
Anchorage Daily News
(Published February 26, 2001)
A crew from the Department of Transportation and Public Facilities camp at Chandalar fires a 41-inch, 40-pound round to set off avalanches while the road over Atigun Pass is closed. Avalanche technician Reid Bahnson watches at left with his back to Steve Brunaski. Earl Ratliff fires the gun.
ATIGUN PASS -- State avalanche expert Reid Bahnson vaulted on top of a waist-high snow berm along the Dalton Highway. Then he wallowed up a ridge in the middle of one of the most slide-prone highway passes in the world.
In 8-degree air, Bahnson wanted to gauge the treacherous snowpack along the 4.5-mile cut through the Brooks Range, about 330 road miles north of Fairbanks. One step would crunch into the wind-hardened surface, almost holding his weight. The next would punch through, plunging Bahnson to his crotch.
About 10 yards up the slope, Bahnson shoveled out a shallow pit. Beneath the stiff cake on the surface lay a mass of unconsolidated crystal, snow as faceted as tiny diamonds. It was like digging in white sand.
"Bottomless depth hoar," Bahnson declared as he scooped up a mound of the glittery stuff in his gloves.
For the 4,800-foot Atigun Pass -- where the 414-mile haul road creeps beneath 2,000-foot mountain faces and 40 to 50 avalanche paths in a steep reach across the Continental Divide -- the prognosis was as chilling as it was common.
The next big wind could trigger avalanches large enough to slam shut Atigun Pass.
"It's waiting for the big one," Bahnson said.
At 68 degrees north latitude, Atigun is the northernmost highway pass in Alaska. No other pass in the world climbs so high so far north with so much industrial traffic. It's a place where frigid weather and high winds create almost perpetual instability. Every longtime trucker or snowplow driver has been hit or stopped by an Atigun slide.
By the first week of February, a few weeks of unseasonable calm had left Atigun's slopes stockpiled.
"It's been almost 10 years since we've had snow this deep on the hillside without a wind storm," Bahnson said. "I haven't wanted to go very far away for a long time. ... All it's doing is waiting for that trigger."
As the seasonal avalanche technician with the state Department of Transportation and Public Facilities, Bahnson has the job of pulling that trigger under controlled conditions with state crews and a 105 mm recoilless artillery rifle. A former patrolman in the Rocky Mountains and Alyeska Resort's snow safety manager, Bahnson has been trying to anticipate avalanches for nearly 30 years.
In a few hours, he would oversee another shoot to nail "the sweet spot," trigger a few slides, peel some dangerous layers from the slope.
"We've got a really bad layer cake right now," Bahnson said. "When wind comes up, we're going to have a mess on the road. But we know what we're dealing with, and we have the gun, so we can deal with it. ... We can make the (future) slides smaller by removing a few slices of the onion now."
Keeping it open
Clearing out avalanche paths looming over haul road truck traffic is only the most explosive chore on the Dalton Highway's maintenance to-do list. Spread among six remote camps from the Yukon River to the North Slope's coastal plain, 60 to 70 DOT crew members work week-on, week-off shifts year-round to maintain what may be the most intensely used gravel highway in the world. With a $6.6 million annual budget, the crews blade and patch the gravel surface during summer, then fight drifting snow and slick spots during winter.
The task of keeping the Dalton open year-round has evolved over the years, according to longtime maintenance supervisor Dwight Stuller. Decades ago, the road would disintegrate each spring into a 20 mph corridor with flagstones and ruts -- "the period when we go from heroes to heels," Stuller called it. In winter, the highway often closed for two or three days at a time. Now the road has a better record, especially during winter, according to several truckers driving the highway in February.
"I think they've been doing a good job," said Fred McMillan, one of the most experienced truckers on the highway. "They're the ones who come out and get you when you get stuck. ... Since they started doing avalanche control, (blockages) have just about stopped."
Stuller said the improvements have come incrementally.
"Our equipment has gotten better," he said. "Our people have gotten better. We have upgraded (bunkhouses) so that they're clean and cheery. ... I think we have a better work force."
Winter maintenance attacks snow -- icing on grades, drifting on flats, avalanches in the mountains. Over the years, the department has worked out a few tricks, Stuller said. During the 1980s, Stuller's crews developed a technique called ice paving -- laying down a surface of ice embedded with gravel plowed from the shoulders.
But the most dramatic winter chore has always been keeping Atigun Pass cleared of snow avalanches for the estimated 3,700 trucks that pass each month between Fairbanks and the North Slope oil fields.
Avalanche shooting day had begun at 6 a.m. when Bahnson and maintenance foreman Wilbur Buckler drove to the pass. The white slopes gleamed -- silent and still in the 3 degree temperature. But the road was clear, marred only by slick spots possibly caused by truckers hitting trailer brakes and polishing up the road.
Bahnson had seen enough.
"Just about anytime we can go up and shoot and knock snow down and make it come down to the road," Bahnson said. "But does it do any good?"
That day's shoot, he said, would show him which slopes were poised to cause the biggest problems during the next inevitable wind storm.
The procedure had a militaristic precision. Bahnson, a former U.S. Army tank commander, checked the weather and logged in his plans. He gathered 10 4-foot-long "bullets" from a storage shed and took them into the cavernous DOT shop to warm them up. Using a satellite phone (which he had to tune in by driving around in the Chandalar camp work yard), Bahnson called Alyeska Pump Station Four and the Federal Aviation Administration to warn them.
By 11 a.m., DOT crew members had blocked the road. Bahnson and two crewmen -- Earl Ratliff and Steve Brunanski --had hoisted the 11-foot-long rifle to a permanent mount along the south fork of the Chandalar River and began to sight it in.
Manufactured as an anti-personnel weapon by the U.S. Army, the 105 mm recoilless artillery rifle has become a standard tool in U.S. avalanche control. When the bullet blasts into the slopes, 4.5 pounds of TNT detonates, shattering the casing into shrapnel.
Bahnson and the two other commenced to shoot. "Clear to the front! Clear to the rear! All clear. Ready to fire. Fire!"
The explosive shot blasted flame from the rear into a 100-foot-long "kill zone" and was so intense that it struck with physical force, producing a sharp, unpleasant blow to the chest. It propelled the bullet toward a slope some 1,200 yards across the valley and a few thousand feet up the slope. The snow blackened on the mountain, followed within seconds by the dull report of the explosion.
In the dim light, that distant slope appeared to give way. But Bahnson hardly hesitated, commencing with the second round. Within 20 more minutes, the crew fired 10 shots at the starting zones of nine slide paths, the furthest hidden in the clouds at a range of about 3,500 yards.
Then Bahnson jumped into a DOT pickup to drive up the pass. As he drove, he eyed the slopes above the car. Several had slid partly down the mountain, and one had spilled on the highway. Snow had covered the southbound lane, piling up 3 feet deep in places.
"This is about what I'd expected," Bahnson said. A few slices removed from the onion. He pulled up next to Buckler, parked in the pass and told him the results. In a moment, Buckler had radioed for the state grader.
"It's one lane," he radioed a line of southbound truckers, parked in a row at the pass. "You can go on down."
They were willing. "I'll follow you down," one radioed the leader as three trucks idled past Bahnson and began the descent past the rumpled debris. "Don't lead me astray now."
"Don't you want to go over the side?"
Reporter Doug O'Harra can be reached at ADN Article or at 907 257-4334.
The mountains of the Brooks Range glow around the Chandalar camp on a clear February evening.
Fred McMillan's truck makes the slow climb over Atigun Pass on the way to Deadhorse. An almost full moon makes the mountains of the Brooks Range glow. The Dalton Highway passes 40 to 50 avalanche paths through Atigun Pass.
Robert Borba works on a plow inside a garage at the Department of Transportation and Public Facilities camp at Chandalar. Sixty to 70 crew members at six camps from the Yukon River to the North Slope maintain the Dalton Highway.
Steve Brunanski, front, and Earl Ratliff press their ear protection close to their heads as avalanche technician Reid Bahnson fires the 105 mm recoilless artillery rifle toward the mountains of Atigun Pass.