Drivers on Interstate 70 may get a preview of a possible future traffic control system at the Eisenhower Tunnel Saturday, when transportation officials are slated to test the new stop-and-go metering model.
But to test drive a system designed for heavy congestion, the Colorado Department of Transportation will have to cause a short traffic jam.
"We want to build up a few people on the west side (of the tunnel) and see how they respond," CDOT Region 1 engineer Peter Kozinski said. "(We want to) see if they can follow the instructions, the layout and see if they understand what we're trying to do."
Metering is the process used to prevent gridlock inside the tunnel when heavy traffic builds up on the highway. The new system would keep traffic flowing slowly though the tunnel by alternately releasing cars from four lanes into the two-lane facility, rather than stopping traffic for up to 20 minutes at one end while traffic clears out inside.
"That would be similar to what you see on the ramp meters in the Denver metro area," CDOT spokeswoman Stacey Stegman said.
On Saturday, transportation officials will only run the new metering system for a single cycle. The entire test is expected to take no more than half an hour.
"We'll stop traffic and allow it to queue up using the existing system," CDOT traffic engineer Clark Roberts said. "After the queue backs up, then we'll go into metering and see how quickly we an flush it out. It will give us an idea of how it's going to work."
If Saturday's test goes well, officials will look at testing the new model again on at a busier time.
Metering continues to be an unpopular but, according to CDOT, necessary feature of the Eisenhower Tunnel.
"The problem with metering is people don't understand it," Stegman said. "People still think it's because of air quality (in the tunnel) or something like that. It's for safety."
The system of metering is intended to prevent bumper-to-bumper traffic inside the shoulderless tunnel to ensure first-responders have access to the entire facility in the event of an emergency.
"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."
The new style of metering falls along the lines of similar low-budget solutions proposed to address frequent traffic backups on the interstate.
The idea of going slower to go faster was first tested last winter through the rolling speed harmonization program, also known as pacing, in which law-enforcement vehicles led groups of vehicles at a slightly lower controlled speed during heavy congestion with the intention keeping traffic flowing through the corridor.
The pacing program was discontinued after only a few weekends after data failed to show conclusively that it was improving traffic flows.