Jon Murray / The Denver Post
A 12-mile construction zone will return to Interstate 70 near Idaho Springs this week as the state adds another tolled express lane to the busy mountain highway.
The new shoulder express lane will be built on the westbound side, mirroring an eastbound lane that opened in late 2015. The new lane, expected to open in early 2021, will go from the Veterans Memorial Tunnels to the U.S. 40 exit at Empire Junction.
The $70 million project will widen portions of the highway to accommodate the narrow lane, which will revert to being a shoulder at off-peak times. Similar to the eastbound express lane, the Colorado Department of Transportation will set varying toll rates aimed at keeping traffic moving in that lane at times of high traffic, especially in the winter and summer. The existing two westbound lanes will remain free, and the tolls collected will help pay off the project.
The project also comes with shortcomings. Among them is that logistical challenges and a space crunch will keep CDOT from starting the express lane more than a mile earlier, at the Floyd Hill exit. That means a bottleneck will still exist on that downhill, where the westbound highway decreases from three lanes to two, before the express lane picks up at the twin tunnels.
Graham Construction of Denver is expected to begin construction Monday, and officials say they expect occasional westbound lane closures during low-traffic periods. Crews will use the closed eastbound express lane to stage equipment, reducing the need for closures of active lanes.
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