A system of alternately releasing cars from four lanes into the two-lane Eisenhower Tunnel might be more effective in preventing gridlock inside the facility than the current 20-minute metering system, transportation officials say.
The Colorado Department of Transportation is continuing to explore ways to keep cars flowing through the tunnel when traffic stacks up on Interstate 70. A new proposal would have flashing red-and-green stoplights allowing traffic to trickle into the tunnel more slowly, rather than stopping a wall of traffic for longer periods and waiting for the traffic inside the facility to clear out.
"We do plan to try a more efficient way of metering," CDOT spokeswoman Stacey Stegman said. "That would be similar to what you see on the ramp meters in the Denver metro area."
Traffic would be split into four lanes in both directions at the eastern and western entrances to the Eisenhower Tunnel. Individual lanes would then be alternately released to proceed forward.
But transportation officials aren't making any policy changes. The new system of metering is just an idea that may be tested out during peak traffic in the future, Stegman said.
"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.
But reaction from drivers and travel time statistics were too mixed to call the program a success.
"We showed some days it made a big difference," Stegman said. "Some days we couldn't quite measure the benefit."
The program has been discontinued this winter, although some regional law- enforcement agencies will still control traffic speeds along the corridor.