Experts recommend $55M plan for Twin Tunnels on I-70
The Denver Post
Aspen, CO Colorado
GOLDEN, Colo. – For a relatively modest $55 million, CDOT could make permanent highway improvements to reduce congestion on Interstate 70 in and around the Twin Tunnels near Idaho Springs, officials said Friday.
After weighing several alternatives, a team of construction experts convened this week by state transportation officials settled on a preferred option that calls for widening the eastbound bore of the Twin Tunnels to three lanes and adding a third lane to eastbound I-70 between the east end of Idaho Springs and the base of Floyd Hill.
The option also includes flattening out the 45 mph curve in the eastbound lanes of I-70 just west of the Hidden Valley exit to allow for 55 mph traffic.
The plan would probably scuttle efforts to address peak-period congestion on I-70 with “zipper lanes.”
Last year, the Colorado Department of Transportation looked at the option of converting a lane of westbound I-70 on both sides of the Twin Tunnels to a reversible eastbound “zipper lane” that would help relieve congestion, especially on Sunday afternoons in the winter.
CDOT found that plan would cut travel times between Georgetown and Evergreen in half on the limited number of winter Sundays but would double the travel time for westbound motorists.
Peter Kozinski, an engineer on CDOT’s I-70 mountain corridor team, cited the advantages of the plan put forward Friday over the zipper-lane alternative, which carried a cost of between $25 million and $40 million.
“Why spend $25 million to $40 million for 17 days a year when I’m giving you three lanes, 365 days a year for $55 million?” he asked.
“That’s the selling point,” added Idaho Springs Mayor Jack Morgan.
During the roughly two-month construction period that would be needed to widen the tunnel bore, eastbound lanes of I-70 would detour to the south on reconstructed frontage roads – the old U.S. 40 and a county road, officials said.
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