ANCHORAGE — Climbers with crow bars could rappel down canyon walls above an Alaska highway as early as next week in the first phase of a $13 million project to keep rock from hitting drivers.
A contractor for the Alaska Department of Transportation will scrape and blast rock above a 3-mile stretch of the Parks Highway just north of the entrance to Denali National Park to take down loose rock that could smash a car or start a rockslide.
“There are rock-blockers in place,” DOT spokeswoman Meadow Bailey said. “They protect the road from rocks falling and then bouncing onto the road. That said, frequently there are large rocks that end up on the road.”
The Parks Highway is the main land route between Anchorage and Fairbanks. The canyon north of the park entrance is one of the most scenic sections, with a rock wall on one side and the Nenana River, a favorite for whitewater kayakers and rafters, on the other.
But when a contractor began work last summer to reconstruct the highway, company officials worried that vibrations from heavy equipment would send rock tumbling.
“They weren’t comfortable working under this rock fall,” Bailey said.
The state consulted with federal highway officials and brought in a specialist to review the canyon.
“They identified 11 areas that were concerning, and of that, five were very concerning,” said Bailey, noting that rock in the five areas could come loose at any point.
“The resulting slide could be something that causes a disruption to traffic or it could be larger than that — road damage,” Bailey said.
What was supposed to be a two-year road reconstruction project will now take four years.
In the first phase, in a process referred to as “scaling,” climbers will use pry bars and other tools to knock down loose rock. To minimize disruption to hotels and businesses near the park entrance, including tour companies that shuttle visitors on river trips and four-wheeler expeditions, the work will be done at night.
Crews will hold up traffic for the rock work, clear the road, and allow traffic to pass at 45 minutes after every hour through the night, Bailey said.
In mid- to late September, after the visitor season winds down, the contractor will blast canyon walls to remove more rock. The early estimate is that 75,000 cubic yards, equal to about 675 covered rail hopper cars, will be removed.
The federal government is picking up 93.4 percent of the rock fall mitigation with a 6.6 percent state match, Bailey said.
