After more than three months of closing eastbound and westbound I-70 for up to 30 minutes at a time, the Colorado Dept. of Transportation has completed blasting operations in the eastbound Twin Tunnel near Idaho Springs. 

The Twin Tunnels project is one of the first projects under way to improve the safety and mobility along the I-70 mountain corridor. The project includes adding one eastbound lane between East Idaho Springs and U.S. 6 and expanding the eastbound bore of the Twin Tunnels.

An estimated 19,700 cu yd of rock has been removed from the 635-ft-long tunnel. Blasting operations began on April 19 to remove the rock from the tunnel bore. Crews performed an average of six blasts per week, totaling 70 blasts this year. Blasting occurred at various times of day depending on the traffic volumes and rock conditions in the area.

The final blast on the eastbound tunnel occurred July 29, but crews anticipate a few periodic blasts through the end of the year to clear any additional rock that may inhibit construction activities. 

“The completion of blasting at the Twin Tunnels is a significant milestone and has been one of the largest challenges we have faced so far in the corridor,” said Jim Bemelen, CDOT I-70 Mountain Corridor Program Manager. “We still have a lot of work on the Twin Tunnels project and on other projects throughout the area to improve the safety and decrease congestion on I-70.”

Although daily blasting is complete, construction near the Twin Tunnels will continue through the end of the year, which may include a periodic blast. In addition to widening the eastbound tunnel bore and adding a third lane, the project will reconstruct the eastbound I-70 bridge over Clear Creek to help flatten the roadway curve at Hidden Valley.

With an estimated 300 accidents occurring in this area each year, this part of the project is designed to enhance safety while facilitating better traffic flow.

The contractor is a joint venture of Kraemer and Obayashi.