CDOT: Metering keeps tunnel clear in case of emergencies |

CDOT: Metering keeps tunnel clear in case of emergencies

Summit Daily file photo/Mark Fox

It was midday Jan. 3 when a car hauling a U-Haul-style trailer caught fire inside the Eisenhower Tunnel. Before rescue crews arrived, the vehicle was engulfed in flames and the tunnel filling with smoke.

Fortunately, the driver was able to escape the vehicle and, though it was Monday following a holiday weekend, traffic on Interstate 70 near the tunnel was light. Rescue crews were able to get to the scene to extinguish the flames.

But on a peak-traffic day, without a system of metering cars, the situation might have been more complicated or possibly even fatal.

So to ensure that they are always able to respond to an emergency inside, Colorado Department of Transportation crews implement a metering system, a process of holding cars at one end so traffic never backs up through the tunnel.

“The primary reason we do it is for safety,” CDOT spokesman Bob Wilson said. “What’s critical is to avoid a gridlock situation within that facility. It’s only two lanes of traffic in each direction. There’re are no pull-outs, there’re no shoulders. So we can’t allow those backups to occur because that wouldn’t allow us to respond to any kind of emergency.”

Metering usually happens on eastbound lanes on peak travel days, particularly Sunday afternoons and holidays in both the summer and the winter when skiers or tourists are heading back to Denver. Traffic is generally held up to 20 minutes as needed until the tunnel clears out.

CDOT officials begin metering the tunnel when volumes increase to between 2,800 and 3,100 vehicles through the tunnel per hour, depending on how the traffic is flowing. Issues such as accidents or bad weather can also cause backups bad enough to require metering.

CDOT holds traffic by activating a stop light just outside the tunnel, which causes already slow-moving traffic to stop. Wilson said metering, a process that has been in place for 20 years, does not usually cause drivers additional delays because traffic is moving so slowly on the other side of the tunnel as well.

On busy Sunday afternoons CDOT stops traffic an average of three to six different times.

Westbound traffic is sometimes metered on the east side of the tunnel as well, but usually as a result of accidents or avalanche control operations on the west side of the tunnel, rather than high volumes.

Hazardous material trucks, which cannot travel with other vehicles on the road for safety reasons, also cause delays at the tunnel when their normal route over Loveland Pass is closed. The haz-mat trucks wait at one end of the tunnel until the top of the hour, when traffic is stopped and the trucks are escorted through.

With new technology available, CDOT is better able to inform the public of delays ahead of time through warnings on variable message signs – electronic signs where messages can be updated remotely – the 511 phone update system and online at

Variable message signs are now posted around Summit County on U.S. 6 and Highway 9 to prepare drivers for the delays before they get on the interstate as well.

Traffic and road condition updates are also available online at

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