The Colorado Department of Transportation (CDOT) began experimenting with “pace cars” over the summer and early fall as a way to manage winter ski-weekend traffic, and put the plan into action earlier this week, summitdaily.com reported.
Pacing, also called rolling speed harmonization, involves having a police car travel at a set speed in front of highway traffic.
CDOT launched the program officially for the first time Sunday, controlling traffic speeds through the frequently congested I-70 mountain corridor from Silverthorne all the way to Floyd Hill, where the highway widens to three lanes.
Results of several tests of the program indicate keeping cars moving at a slow, but steady speed on peak Sunday afternoons prevents backups and actually shaves minutes off the drive time, CDOT officials said.
It seems like having traffic travel more slowly than the actual highway speed limit is counterintuitive, but CDOT officials compare the process to draining water through a drain or funnel: If poured too quickly, a large quantity of water will get backed up and take time to drain, but if poured slowly, the water will flow through smoothly.
The pacing program got under way just after 11 a.m. Sunday as traffic hit 1,900 cars per hour through the tunnel and ran 12 miles further than the most recent trial, which tested the program through Empire Junction.
Pacing a packed highway
A total of 24 law-enforcement officers in marked patrol vehicles from the Silverthorne Police Department, Colorado State Patrol and Clear Creek county participated in the pacing Sunday. Authorities split the 39-mile corridor into short sections, with patrol cars from the proper jurisdiction pulling in front of traffic every few minutes, lights activated, and controlling speeds.
Pacing is at its most effective when traffic volumes are at approximately 1,900-2,300 cars per hour through the tunnel. On some Sunday afternoons, ski traffic returning to Denver can get 3,000 cars per hour through the corridor.
CDOT pays for off-duty law-enforcement officers to run the pacing operation and for the patrol vehicles used for the program. Running the pacing program for a single Sunday afternoon costs the transportation department between $4,500-$5,000.
The pacing program will continue to run on eastbound I-70 on Sunday afternoons and some holidays as needed through March or April, CDOT officials said.