Similar to ramp metering used in the Denver metro area and other congested areas, Continuous Flow Metering (CFM) is utilized by CDOT at the Eisenhower-Johnson Tunnels heading eastbound. Traffic is spread from two into four lanes with traffic signals located above each lane. The signals then alternate traffic, efficiently regulating the flow of traffic through the tunnel. They cycle every 4 to 8 seconds so vehicles only have to stop briefly before being allowed to enter into the tunnel. “CFM proved to be more effective at keeping the eastbound traffic moving through the tunnel than by the old way which required all vehicles to stop up to 20 minutes at a time,” said CDOT Eisenhower Tunnel Superintendent Mike Salamon.
The primary reason for metering is the safety of the traveling public. Inside the tunnel, there are only two lanes, no pull-outs or shoulders, and vehicles are wedged together tightly. CDOT does not allow traffic to backup in the tunnel to the point where crews would not be able to respond to a medical emergency, accident, fire, or other problem, in a timely manner.
Have fun out there this weekend!