KEYSTONE, Colo. (CBS4)– If you were stuck outside the Eisenhower and Johnson Tunnels earlier this month because the tunnels closed, you weren’t alone. The tunnels were a part of a blackout on Sunday, Dec. 12 which caused Colorado Department of Transportation operators to close the tunnel for safety reasons.

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CDOT Chief Engineer Steven Harelson said it boils down to them not being able to vent the tunnel if there were to be a fire in the middle somewhere, and that smoke quickly turning the tunnel into a death trap.

“On average we have one fire per year,” Harelson explained.

He went on to say there have been no recorded fatalities, but it’s something they would never gamble with during a blackout.

There is a backup generator, but like a lot of the mechanical working of the tunnel, it’s the same stuff that was put in as the tunnel was built in 1973. The backup power is just enough to power a single fan and lights in the buildings, but that’s it, and that’s not enough to have cars safely travel through.

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So with all of this, why were drivers stuck for more than an hour along I-70?

“It takes a while to get that all back on, right?” Neal Retzer, Resident Tunnel Engineer told CBS4’s Spencer Wilson. “There’s a lot of systems that went down. A mix of all the new systems went down as part of that. But you know, they’re designed to do that.”

Retzer said just like when a circuit breaker trips in your home, the same happens at the tunnel, just on a much larger scale. Getting that all put back on takes time, and confirming the fans are working as they should does too.

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That’s why CDOT is excited to purchase a new generator from a combination of federal and state monies that will be able to power enough fans to theoretically keep traffic moving, even if there are power outages. Retzer says there are hundreds each year, and while they don’t all shut down the interstate, it would make things a whole lot safer and more streamlined for both his team in the tunnel and the drivers going through it.

That generator plan is expected to break ground in the summer of 2022.

Spencer Wilson