As Colorado Department of Transportation officials were contemplating closing the westbound bore of the Eisenhower-Johnson Memorial Tunnel to investigate new ice formations, the source of the problem has been identified, making a closure obsolete.

CDOT Region 1 tunnel program manager Paul Fox said some of the new leaks and ice mounds motorists have witnessed while driving through the westbound portion of the tunnel resulted from a project aimed at pushing water away from the tunnel liner. He said this forced water over the arch of the tunnel and into an exhaust plenum, or an area with dedicated space for air circulation. 

He said once the water pushed into the ventilation area, CDOT crews began noticing icicles on the ceiling and ice mounds in areas of the westbound tunnel they hadn’t seen in the past. 

“Now we have water on the left-hand wall, which in my time (with CDOT) we’ve never had up there before,” he said. 

He said crews are currently working to channel water out of the exhaust plenum.

Fox said CDOT officials were not concerned when they first noticed the new ice formations and still aren’t. 

“It’s just a change. We’re humans — we don’t like change, so when we notice something, we do talk about it,” he said.

He explained the tunnel walls motorists can see are mostly cosmetic and that a bulk of the water circulation happens through piping inside the tunnel. 

“The water (people) see is from the ground, and it’s seeping through our tunnel liner,” he said. “That’s always going to happen anytime you build on a mountain — you just can’t get rid of the groundwater.”

CDOT officials say they look to avoid Interstate 70 closures when possible. According to the agency, the state’s economy takes a $1.6 million hit every hour a significant portion of the highway is closed.

The Eisenhower-Johnson Memorial Tunnel is one of the most well-traveled portions of Interstate 70 in the western part of the state, and CDOT officials say an average of 34,611 motorist pass through it daily during ski season.

The U.S. Department of Transportation does its own vetting of the structural integrity of the tunnel every two years, and CDOT does their own vetting every year, according to Fox.  

He explained the tunnel is shaped like an egg, with an arch at both the top and bottom and a structure similar to a bridge going through it. During inspections, he said, teams are looking for any type of movement in the tunnel, which is largely evidenced by cracks. 

A unique aspect of the Eisenhower-Johnson Memorial Tunnel is its location under the Continental Divide, which Fox said is known for constantly shifting. He said the shifts are minor and can amount to quarter-inch increments over the course of years.

He said people shouldn’t worry about the structural integrity of the tunnel.

Aside from continuing the project focused on the tunnel’s liner and walls into the fall, Fox said people can expect a project involving switching out all the LED lights in the tunnel during summer 2026. Also in summer 2026, CDOT plans to repave the roadways inside the tunnel.

CDOT officials have said the tunnels are prioritized in CDOT’s 10-year plan, which was originally adopted in May 2020. An estimated $53 million has been invested in tunnel repairs since. The agency began a $71-million repair project in June 2023 aimed at repairing and rehabilitating the tunnels, which is slated to wrap up by fall 2025.

There is also an additional $100 million in funds earmarked for future projects on the tunnel.