On Sunday, CDOT will again use police “pace cars” to try to get motorists heading east on Interstate 70 from Silverthorne to slow down, avoid tailgating and smooth out the traffic flow in an effort to eliminate bottlenecks.
The Colorado Department of Transportation calls the concept “rolling speed harmonization,” and Sunday’s test — involving police pacing for about 27 miles from Silverthorne to Empire Junction — follows an earlier one held last month on a Saturday.
CDOT officials said they will get a better sense of the value of speed harmonization from a Sunday test, when eastbound traffic counts on I-70 are much higher.
Silverthorne police will start Sunday’s test around 10 a.m. when a patrol car will enter the highway with lights flashing just east of the Silverthorne interchange and pace traffic at speeds of between 45 mph and 55 mph the eight miles to the Eisenhower/Johnson Memorial Tunnel, according to CDOT’s plan.
At that point, Colorado State Patrol vehicles will take a handoff and become pace cars through the tunnel and down the mountain to Empire Junction, the agency said.
Pace cars are expected to enter the traffic flow every five to 10 minutes and the test is to last until about 2 p.m.
CDOT officials said when speed harmonization was tested last month it “created more uniform speeds for vehicles,” thereby reducing the likelihood of accidents and backups. August’s test ran only from Silverthorne to the tunnel.
Officials said the pace-car technique should help CDOT avoid metering stop-and-go traffic through the Eisenhower Tunnel.
The agency meters traffic when backups cause eastbound vehicles to stop in the tunnel.
Metering involves halting the eastbound flow of cars before they enter the tunnel, so vehicles stopped in the tube can get moving and out of the underground roadway.
For years, state transportation officials have been looking for solutions to I-70’s episodic congestion problems, which are most acute on Sundays or holidays when unusually large numbers of vehicles clog the interstate, especially its eastbound lanes.
CDOT recently considered, and then rejected, a concept called “zipper lanes” that would have used movable barriers to convert a westbound lane to an eastbound traffic flow to speed the flow of vehicles toward Denver.
Officials shelved the zipper-lane concept because modeling showed that while it helped eastbound motorists by offering shorter travel times, it correspondingly hurt those drivers heading west, stacking them up in long lines of slow moving traffic at locations in the mountain corridor.
CDOT plans to test speed harmonization at the end of this year during winter-driving conditions.
Jeffrey Leib: 303-954-1645 or jleib@denverpost.com
