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By Kevin Flynn
Inside-Lane.com

The Colorado Department of Transportation says it will reopen two lanes of Interstate 70 through the damaged rockslide area in Glenwood Canyon by the end of the day Thursday after geologists blasted down a huge boulder and surrounding rock that threatened to fall onto the highway.

However, the opening won’t bring relief to truckers with wide loads. Due to the narrow lanes through the work zone, the two-lane traffic will include a restriction on vehicles wider than 14 feet, according to Fleet Owner.com.

CDOT said Wednesday night that the blasting effort succeeded in splitting a boulder that looked like it might come down from the same area where an early Monday morning rockslide heavily damaged the I-70 bridge deck outside the Hanging Lake Tunnels and closed the highway.

Along with the 20-foot-diameter boulder, other loose rock in the area also came down onto the highway in the blast, and the good news is that means CDOT’s rock scaling crews won’t have to ascend the canyon wall again on Thursday to pick remaining loose rock.

But with all the rock tumbling down, maintenance crews have heavy cleanup work to do and significant roadway repair before the highway, now in its fourth day of being closed, can take traffic again.

CDOT doesn’t yet have a set time for the reopening, but said it would happen sometime late Thursday.

CDOT photo shows most of the debris cleared from the bridge deck, with two gaping holes in the westbound lanes and median area. The eastbound lanes, nearest to the camera, will be repaired first to allow two-lane traffic to resume.

The large boulder was blasted around 6 p.m.

The emergency started early Monday morning, just after midnight Sunday, when large rocks came down onto the I-70 viaduct west of the ramps to and from the Hanging Lake Rest Area. The slide punctured about a half dozen holes and divots in the bridge deck. At this location, the highway is up against the north wall of the canyon but is elevated on a the viaduct as it curves eastward toward the twin portals of Hanging Lake Tunnels across the Colorado River on the south side of the canyon.

The highway crosses the Colorado River and Union Pacific Railroad, just west of the Shoshone Dam. The debris was scattered over about a 300-foot length of highway.

Gov. Bill Ritter declared the situation a disaster on Monday, allowing the state to go after assistance from the Federal Highway Administration to help pay for repairs.

It is close to the same area where an early morning Thanksgiving rockslide in 2004 did much the same type of damage. Then, CDOT was able to get two lanes of traffic reopened in 31 hours but it had to restrict long trailer trucks for two months while full repairs were made and all four lanes reopened.

In this case, the bridge deck damage was more significant and extends into the eastbound lanes, making it more difficult to use them as a detour. CDOT plans to use emergency contracting to hire a company to make the full repairs.

Scroll around this Google Street View interactive view outside the west portals of Hanging Lake Tunnels to see the cliffs from which the rocks fell.

View Larger Map

Wednesday morning, CDOT used a helicopter to drop off drilling equipment and a generator for the drilling and blasting operations on the unstable boulder. Crews worked on Tuesday to try to bring the boulder down but ran out of daylight up on the cliffs.

“A team of six hiked up 900 feet on the mountainside (on Tuesday) and conducted rock scaling operations (removing loose rock material with pry bars and other equipment) until approximately 5:30 p.m.” CDOT said in a statement. “They were able to safely access the unstable rock needing to be brought down. Losing daylight, crews attempted to pry sections loose and locate areas in which to effectively place and then charge explosives, but were unable to do so.”

In the meantime, with I-70 closed between Dotsero and Glenwood Springs, a detour of up to 150 miles remained in place for cross-state traffic in the I-70 corridor. I-70 in Glenwood Canyon has average daily traffic of 19,800 vehicles a day, according to CDOT traffic counts.

Some of the boulders were the size of semi-tractors and were broken up with explosives before being moved out of the road. One weighed 66 tons. One hole in the westbound lanes was estimated to be 10 by 20 feet, said CDOT spokeswoman Mindy Crane. In the eastbound lanes, there was a six-by-six-foot hole.

There might have been a foreshadowing of the slide earlier in the weekend. Motorist Chuck Hickey was headed toward the canyon westbound on Saturday morning when he heard a radio traffic report that I-70 westbound was closed at mile marker 125, the exact location of today’s slide, due to rocks. Because Vail Pass was closed by an accident, Hickey detoured at Copper Mountain to Leadville on CO 91, then took U.S. 24 over Tennessee Pass to I-70 at Minturn.

“I had KOA on and they reported it,” Hickey reported on Facebook. “Said it was westbound I-70 closed at MM 125. But when I got back onto I-70 at Minturn, they no longer were reporting it and when I went through there, there were no trucks or anything. But people in Leadville were talking about it when I stopped.”

CDOT has an operations center inside the Hanging Lake Tunnels that is staffed around the clock to manage traffic. Read an article about the center here.

I-70 through Glenwood Canyon is an internationally acclaimed stretch of roadway that won award for its context-sensitive design and construction. Because of the high unstable cliffs, there are areas prone to rockslides. Read this comprehensive photo-filled feature about the history of I-70 in Glenwood Canyon at Matt Salek’s Highways of Colorado site.