The east portals of the Eisenhower-Johnson Memorial Tunnel on Interstate 70.

Blowing snow and resulting traffic backups on Interstate 70 on Saturday prompted seven separate stoppages totaling three hours at the westbound entrance to the Eisenhower-Johnson Memorial Tunnels under the Continental Divide.

It brought an avalanche of driver complaints and a review by the Colorado Department of Transportation of the messages it puts on its electronic signs.

But don’t expect the practice of halting traffic to end. It’s all about your safety.

“It’s very much to assure ourselves that we can respond to an emergency in there,” said Mike Salamon, CDOT’s superintendent at the tunnel. The 1.7-mile, two-lane bores have no shoulders and no way for emergency vehicles to maneuver around stopped cars. “How could anybody ever explain watching a ski bus burn in there and we couldn’t get to it? When traffic starts to fill up to about half the tunnel, we shut it down.

“This is an absolute safety action,” said Salamon. “We have never had a fatality inside the tunnel, due in part to some of the things we do like this.”

The traffic stops, which CDOT calls “metering” traffic through the tunnels, happened Saturday between 3:30 and 8:30 p.m. They were prompted by heavy traffic backups originating near the Silver Plume grade that slowly backed the line of cars up the hill to the U.S. 6 Loveland Pass interchange, within sight of the tunnel.

“Traffic started queuing somewhere down around Silver Plume probably due to blowing snow and probably some inexperienced drivers,” Salamon said. “Eventually it came to a dead stop and began backing into the tunnel. If we didn’t stop traffic from entering, it would have continued to back up clear through the tunnel and down the west approach. We have never allowed that to happen.”

As annoying as the stops might be for drivers stuck on the steep grade of the Straight Creek approach – especially when it is snowing and it might be difficult for uphill vehicles to regain traction – CDOT says the traffic stops will continue whenever there is a risk of a traffic jam bringing cars to a dead stop inside the tunnels. And since the stalled drivers merely catch up to the traffic jam on the other side once CDOT releases them, it says there is no added delay for drivers. They don’t get home any later than they would have.

“If we had just let nature take its course, you still would have been stuck downstream, but I wouldn’t have done it to you,” said Salamon.

Looking down from U.S. 6 on the east side of Loveland Pass toward the Eisenhower-Johnson Memorial Tunnel. CDOT Photo.

CDOT stops cars from entering the eastbound tunnel once a back-up of downhill traffic on the Clear Creek side works its way back to the Loveland Pass interchange, about a mile below the portal. When that happens, CDOT stops traffic short on the steep grade of the Straight Creek valley on the west side. Traffic already moving through the tunnel at the time of the stoppage adds to the back up and, on occasion, vehicles sometimes end up idling at a stop inside the tunnel.

With a nod to you highway purists out there and for the education of casual readers, the eastbound tunnel that was affected by Saturday’s closure is actually the Edwin C. Johnson Memorial Bore, which opened in 1979. “Big Ed” Johnson was a longtime Colorado governor and U.S. Senator who was instrumental in getting I-70 extended west from Denver across to Utah. I-70 as originally proposed was to have ended at Denver’s Mousetrap interchange with Interstate 25. The westbound tunnel is the Eisenhower Memorial Bore, named for President Dwight Eisenhower, who signed the interstate highway system into law and who made Denver and Colorado his frequent summer getaway. It opened in 1973.

At a maximum elevation of 11,158 feet at the west portals, the Eisenhower-Johnson Memorial Tunnel complex is the highest point on the entire U.S. interstate highway system. There is an excellent account of the tunnels’ history at the I-70 page on Matt Salek’s Highways of Colorado web site.

CDOT’s collection of tunnel facts and figures is here.

Salamon said air quality isn’t much of an issue even if traffic does get stopped in the tunnels. Each of the 28 exhaust fans in the tunnel system is capable, he said, of moving a half-million cubic feet of air per minute.

“We can create hurricane-force winds in our air duct, approaching 90 miles per hour,” he said. That would easily clear any deadly carbon monoxide buildup from the tunnels.

The principle risk is an event like a vehicle fire, accident or medical problem inside the tunnel when traffic is dead stopped. He said the tunnels average two vehicle fires a year, some of them major conflagrations.

“The main reason is you can imagine what if we had an accident, a fire or a medical assist halfway through the tunnel and we have traffic at a dead stop,” he said.

A few times, claustrophobic drivers have come to a stop inside and jammed up traffic. Salamon said CDOT workers have had to drive those cars out on their own.

Saturday’s seven metering events were noteworthy for their number and duration. Salamon said CDOT doesn’t have readily available records to total the number of stoppages over time, but Saturday’s were among the worst.

One stoppage alone lasted 40 minutes. The average for all seven was 22 minutes.

“It is happening with more frequency as we see more and more traffic,” he said. “It can happen just as easily in the summertime.” Summer traffic counts are generally higher at the tunnel. July and August usually have the highest traffic counts, followed by March and January. The highest hourly traffic count in one direction was 3,450 vehicles – essentially 100 percent of capacity.

You can look at monthly traffic counts at the tunnel here.

“I talked to a few very very angry folks,” Salamon said. “But with the volume of traffic and the weather conditions, it’s going to happen and I don’t know of any way to solve it.

“If we had allowed traffic to back into the tunnel, during that one time it would have taken 40 minutes to get thought the tunnel, and that is unacceptable,” Salamon said.

On Saturday, the line of cars snaked back down to Silverthorne, and Salamon said some drivers opted to bail on I-70 there and take Loveland Pass instead. That eventually added to the congestion problem as those drivers re-entering I-70 beyond the tunnel delayed the break-up of the traffic jams that were causing the stoppages on the west side

CDOT said its variable message signs in Summit County approaching the hill to the tunnel carried the words, “Heavy traffic ahead; expect delays.”

CDOT officials met Wednesday to discuss the Saturday events and, among other things, whether the messages should have been more specific, such as “Periodic tunnel closures ahead; consider delaying your trip.”

There is no practical fix for the problem. Even adding a third bore or widening the tunnels wouldn’t prevent the traffic backups on the two-lane downhill highway segments, and widening the entire highway is both prohibitively expensive and politically unpopular. CDOT has added ramp meters to some entrance ramps in an effort to prevent clogs at interchanges, and has added ski-season courtesy patrols to clear stalled or wrecked vehicles. Its dynamic message signs can help drivers decide whether to delay their departures until there is less traffic.

Long-range, planners are looking at lane additions in selected segments and building a transit system of some sort along the corridor from Denver to as far as Vail.