CDOT plans better use of I-70 message signs to help drivers during Eisenhower Tunnel traffic stops

Motorists crossing the Continental Divide at the Eisenhower-Johnson Memorial Tunnel on Interstate 70 may soon be getting more specific warnings about tunnel closures during heavy traffic, following Saturday’s record three hours of traffic stops to keep idling cars out of the tunnel.

The Colorado Department of Transportation is coming up with different wording for the overhead lighted signs called Variable Message Signs that would make drivers more aware that they might have to come to a stop on the highway while traffic jams ahead clear up.

When CDOT needs to shut off traffic flow through the tunnel, the message boards will be modified to say something like “20 minute traffic stops at tunnel; 4 hours+ to Denver,” said CDOT spokesman Bob Wilson.

“This is just a draft message – we still need to discuss the exact wording and some protocol – but we’re moving forward with the metering messaging, something that we haven’t done in the past but will now do.,” Wilson said.

On Saturday, when CDOT imposed seven traffic stops in the eastbound lanes outside the tunnel entrance totaling three hours over a five-hour span, the VMS messages said: “Heavy traffic ahead; expect delays.” That wasn’t specific enough to prompt many drivers to delay their ascent up the steep Straight Creek grade that approaches the tunnel from the west side. The line of stopped cars wound down to Silverthorne and a number of motorists opted to detour around on U.S. 6 via Loveland Pass.

CDOT has a safety-driven policy of not allowing traffic jams to back up into either bore of the 1.7-mile tunnel complex – the highest point in the entire U.S. interstate highway system at 11,158 feet above sea level.

The concern, says Mike Salamon, CDOT’s tunnel superintendent, is that emergency responders would not be able to get to a vehicle fire, accident or medical problem inside the tunnel if traffic is at a dead stop from end to end. The two-lane bores have no shoulders to drive along.

The practice is instituted when downhill traffic slows and the line of traffic starts to back up to within a mile of the tunnel portal. To avoid having stopped cars inside, CDOT prevents more traffic from entering the other side.

The longest stoppage on Saturday lasted 40 minutes. The average of all seven closures was 22 minutes.

CDOT calls the practice “metering” traffic. But as opposed to ramp meters that dribble one or two cars at a time down an entrance ramp onto a busy freeway, metering at the tunnel means full stop until traffic jams downstream break up. How long that takes depends on the circumstances. Salamon said drivers detouring over Loveland Pass actually made the closures last a bit longer as they added to the jam headed down toward Silver Plume.

Wilson said CDOT hadn’t been as specific on its VMS messages before now. One problem is that CDOT often needs to convey several messages to drivers during bad weather. Primarily, it is obligated to inform truckers when the chain law is in effect, since failure to use chains can incur heavy fines for trucks. Truck accidents or slides are a major contributor to congestion on I-70 in the winter.

“A couple of the VMSs have to remain for chain law messaging, so not all our signs will be able to have the tunnel stop information when the chain law also is in effect,” Wilson said.

Between Copper Mountain and the tunnel’s eastbound entrance, CDOT has five VMSs installed over the eastbound lanes. But two of them are on the uphill grade, beyond the point where motorists can change their minds about pulling over in Silverthorne.

CDOT’s CoTrip.org web site has a map on which you can read in real time the current messages displayed on any VMS in the state. You can access that by clicking here, then choosing the “Signs” tab on the right.

Wilson said CDOT will also make more use of CoTrip.org and its 511 traffic information phone line to disseminate information about tunnel “metering” closures. One problem inherent in stopped traffic is that CDOT’s roadside devices that monitor traffic speeds don’t calculate information from stopped vehicles. The devices need to track vehicles from one point to another in order to calculate speed and travel times for the message boards. So accurate messages about how long the drive to Denver will take can’t be obtained during tunnel stops.

CDOT uses several different devices to electronically read a vehicle’s toll transponder to calculate travel speeds and times. Some were featured here in a recent Inside Lane slide show presentation on high-tech roadside equipment.