IDAHO SPRINGS, Colo. (CBS) – A project to widen the eastbound lanes of the Twin Tunnels near Idaho Springs means drivers heading home from the mountains will encounter a detour for the rest of the year.

Traffic now goes over a new bridge along the old Highway 6 frontage road before getting back on Interstate 70 as part of the $100 million project.

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While some businesses worry it could hurt tourism, people who have worked for decades to ease congestion on I-70 say it’s worth the pain.

“It’s a long time coming, getting some new capacity on the I-70 corridor,” said Margret Bowes, manager of the I-70 Coalition Project. “This is absolutely one of the biggest pinch points on the I-70 corridor.”

That coalition is a a non-profit that covers 100 miles and is made up local governments and businesses that want to keep fix the ongoing congestion problems on I-70.

“This isn’t going to solve all of the I-70 congestion issues but it’s certainly a good step in the right direction,” said Bowes.

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And she said she understands business worries about summer tourism. “There’s a lot of concern but I think it’s important to note the mountains are still going to be open this summer.”

But traffic won’t always be moving. All traffic will be stopped both eastbound and westbound for up to half an hour at a time to do the work inside the tunnels.

“The blasting is scheduled to continue through August,” said Mindy Crane with the Colorado Department of Transportation. “Then through the rest of the year it’s really widening the tunnel as well as eastbound I-70.”

The westbound closures will last a little longer, because once the blasting is done crews must inspect the work before re-opening the interstate to traffic.

Crews work on the Twin Tunnels on Tuesday. (credit: CBS)

Crews work on the Twin Tunnels on Tuesday. (credit: CBS)

And when blasting is under way, it’s not just interstate traffic that will be delayed. CDOT will stop river rafters on Clear Creek.

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Officials with the Colorado Department of Transportation wants to make sure drivers are informed so they are posting updates on The site includes a place to sign up for email and text alerts.

Crews work on the Twin Tunnels on Tuesday. (credit: CBS)

Crews work on the Twin Tunnels on Tuesday. (credit: CBS)