A light at the end?
Glenwood Springs correspondent
Aspen, CO Colorado
GLENWOOD SPRINGS ” When Gary Coffey was growing up in the ’70s and ’80s, he and his family would drive through Glenwood Canyon on their way to Lake Powell in Utah.
Decades later, Coffey is the superintendent for Concrete Works of Colorado, with which the Colorado Department of Transportation contracted to repair the 70-foot-long crack in the concrete above the Hanging Lake Tunnel.
“I’ve driven this tunnel since I was a kid, and I wanted to work on this project back when they were building the interstate,” said Coffey, of Lakewood, Colo. “I love structures. I watched this thing being built from start to finish.”
Joe Elsen – a program engineer for CDOT who is overseeing the design and construction of the repair project – also has a vested interest in the repairs. He worked 11 years on the tunnel during the Interstate 70 construction project that was formally dedicated on Oct. 14, 1992.
“I started in the spring of ’83 working on this thing,” he said. “I did surveying, inspection, and was a project engineer.”
Federal Highway Administration discovered the crack during an inspection in 2006, prompting Elsen, CDOT and a crew of designers and geologists to devise a repair procedure during the winter that was officially put into place in March. A rockfall in January 2002 near the Hanging Lake Tunnel contributed to the crack, Elsen said.
“It’s important to note this is a very unique situation,” he said. “And a very complicated structure. We take our work very seriously – that facility is manned 24-7.”
The tunnel’s eastbound lanes were closed on March 30, and Concrete Works of Colorado began repairs in April. Traffic has been diverted to the westbound lanes through the tunnel.
“I don’t think the thing could have gone any quicker,” Elsen said. “It’s been a really good project, and it’s been very tight scheduling so it remains safe.”
The crack is being repaired with two large slabs of concrete – one above the crack and the other below – connected by steel bars through more than 800 holes drilled through the affected slab.
“This whole slab weighs three million pounds, with 25 million pounds of earth on top of that,” said Elsen, inspecting the repair from below the crack. “We’re sandwiching the fracture.”
The total cost of the project is estimated around $4.6 million. The original estimate came in around $2 million, Elsen said. The project required heavy equipment to be shipped from the Front Range by rail.
“Initially, we didn’t know what we were up against,” he said. “As we got into it more, there was a change in the repair scope. The earth removal cost stayed the same but the coring and steel rod work was more. There were a lot more holes. The work was going to be limited to where the crack was. Bracing the thing was a half million dollars, plus additional railroad costs.”
Excavation to access the connector section of the tunnel above the crack took Concrete Works of Colorado three weeks alone to complete. Concrete workers have been coring holes through reinforced concrete since then.
“It’s just tedious, time-consuming coring. It’s just time-consuming is what it is,” Coffey said. “Number one, we have to secure the area – we had to make it safe. This is a pretty unique situation.”
Elsen said the project has been running smoothly, and CDOT projects the reopening of the eastbound lanes of I-70 through the tunnel by Oct. 1.
“Our maintenance people said, ‘You better be done before the snow flies,'” he said. “It gets extremely complicated when the snow flies.”