Highway reopens in Colorado

Three days after a rock slide in a narrow Colorado canyon rained down massive boulders onto Interstate 70, severing one of the main east-west routes through the country, the road reopened Thursday.

State officials were able to open one lane in each direction through Glenwood Canyon in western Colorado, thanks to temporary repairs and the blasting of a giant boulder that had remained perched precariously above the road.

However, it could take several months to permanently repair and fully reopen the damaged highway, used daily by up to 25,000 vehicles. Officials said they were waiting to receive estimates Friday before determining a time frame.

A similar rock slide in 2004 on the interstate took about two months to repair, said Colorado Department of Transportation spokeswoman Mindy Crane.

For days, the closure has crippled travel along the route, the primary artery between the West Coast and Denver, forcing travelers on a 200-mile detour. Travel will remain problematic, especially for truckers ferrying loads through the state, said Greg Fulton of the Colorado Motor Carriers Assn.

“You couldn’t find a greater choke point than that right now,” Fulton said of the slide area. “In other parts, you could say, ‘We’ll get on the frontage road.’ There is no frontage road around there.”

Just after midnight Sunday, about 20 boulders -- some as large as 10 feet in diameter and weighing 66 tons -- tumbled down the canyon, gouging the road and smashing guardrails. No injuries or vehicle damage were reported.

Crews cleared away the debris and patched holes in the road, but complicating the clean-up was a boulder, 20 feet in diameter, that was balanced on the mountain slope, threatening to tumble down. Geologists used a helicopter to ferry equipment to the site, drilling into the rock and packing it with explosives. After blowing up the rock late Wednesday, officials declared the area safe for travel.

But even as crews worked on I-70, a falling rock struck and killed a motorist Wednesday on the detour route. A 55-year-old woman was headed east on U.S. Route 40 when a single, basketball-sized rock fell from the canyon wall, smashing through the windshield, according to the Colorado State Patrol.

Transportation officials called it a rare incident. “This is a low-risk area for rockfalls,” Crane said. Since 1998, that area on the detour route hasn’t had any recorded rockfalls, she said.

Correll writes for The Times.