CDOT starts widening work for westbound Twin Tunnels project on I-70

Visitors to Colorado’s high country could start seeing lane closures as early as Monday, March 10, for work on the westbound Twin Tunnels project. This Colorado Department of Transportation project will widen the westbound tunnel bore to accommodate future expansion in the I-70 corridor. Unlike last year’s eastbound project, this westbound project will not add a third travel lane at this time.

Before crews can begin the blasting work that will widen the tunnel and remove a portion of the rock face walls above the westbound tunnel, traffic must be rerouted from the westbound bore into the eastbound bore. To accommodate this traffic shift, crews will put down temporary pavement in the center median area on both sides of the tunnel to transition westbound traffic into and out of the eastbound lanes. This center median work will take about a month to complete and requires closing the far left lane of eastbound I-70 during off-peak travel hours.

“With this year’s record snowfall in the mountains we realize how important it is to keep traffic moving during the spring break ski season, so we will only close lanes during off-peak travel times and we will monitor traffic flow so we can make adjustments as needed,” said CDOT Project Manager Benjamin Acimovic.

Along with these off-peak lane closures, preparatory work in the westbound tunnel bore will require putting I-70 traffic in a head-to-head configuration through the eastbound tunnel for overnight work. This will be done several nights throughout March and will involve maintaining two eastbound lanes and one westbound lane.

Other work scheduled to take place in March includes one or two small blasts outside the westbound tunnel to facilitate the extension of a drainage box beneath the highway and two or three days of rock scaling work in late March to prepare for the larger rock face blasts that will begin in April. The blasting operations in March will require stopping traffic in both directions for about 15 minutes while the rock scaling work will require stopping traffic in both directions for up to 30 minutes so crews can safely remove large boulders and rocks from the rock face above the highway.

In April, eastbound traffic will be reduced to two lanes of travel and will move back onto the detour route around the tunnel while westbound traffic slides over into the eastbound tunnel bore. Once traffic is shifted, crews will begin large-scale blasting inside the tunnel as well as rock cut blasting on both ends of the tunnel.

Blasting activities will continue through the end of summer and involve stopping I-70 traffic in both directions. Tunnel blasts require shorter duration stops of about 15 minutes while the rock cut blasts will have a greater impact on I-70 travelers. Following each rock cut blast, crews will need to scale the hillside to remove any loose rocks and debris to keep it from falling on the highway below. This scaling work requires stopping traffic for up to 30 minutes followed by about 45 minutes of free-flowing traffic to clear the queues. This alternating process of stopping and releasing traffic will continue as long as necessary to finish removing blasted materials.

Construction crews anticipate conducting one or two rock face blasts each week and tunnel blasting just about every day of the week through August.

CDOT estimates widening the westbound tunnel now will save $5 million to $7 million because the equipment, resources and detour needed to do the work are already in place. Tunnel widening work is scheduled to be complete by the end of this year and at that time all I-70 traffic will be back in its regular alignment. Project completion is scheduled for summer 2015 when County Road 314 is restored to its original configuration with completed facia walls and an improved recreational trailhead.

For additional project information and details on traffic impacts, call 511, visit www.cotrip.org, text CDOT to 25827 or download the CDOT smartphone mobile application from your App store. You can also visit the project website at www.coloradodot.info/projects/i70twintunnels