Initial Results are Positive for Rolling Speed Harmonization Test on I-70

August 22, 2011 - Central Eastern Colorado/CDOT Region 1 - SUMMIT COUNTY – The initial results of the rolling speed harmonization test conducted on August 13th on eastbound I-70 between Silverthorne and the Eisenhower/Johnson Memorial Tunnel are indicating that this effort does have the ability to create more uniform speeds for vehicles, and as a result, could improve safety, reduce traffic crashes and ultimately improve traffic flow on the corridor.

When rolling speed harmonization is underway, a law enforcement vehicle runs with its emergency lights and merges ahead of traffic to pace vehicles and create more speed uniformity.  Notable results from the recent test:

  • The pacing ran from 10:10 a.m. to about 2:15 p.m.
  • Average Speed:  55 miles per hour (mph) while pacing was in effect.  Between vehicle platoons the speed was 60 mph.
  • Data showed very high compliance and speed differentials were reduced, even between vehicle platoons  – a key determinant since wide variations in speed lead to higher probability of accidents, which in turn increases congestion substantially.
  • After the test was concluded,  vehicle speeds begin to increase to the 70 mph range and higher while trucks continued to average 30 mph and vehicles were traveling at many different speeds in between.
  • Only one driver tried to pass the Colorado State Patrol (CSP) pace vehicle--several times-- but the officer was able to use a loud speaker to gain compliance.
  • The test showed that communication and operational coordination worked well with all parties – CDOT, the Colorado State Patrol and the Silverthorne Police Department.
  • It appears from initial test indicators, it possibly can be another tool to maximize the capacity we have on I-70 with the rolling speed harmonization.
  • If it reduces accidents, and the probability of accidents rises with variable speeds of vehicles, it can be considered a successful way to lower accidents.
  • This test did not adversely affect traffic and it flowed smoothly throughout the test period.  However, the vehicle counts were not that high –  High: 1,479 vehicles, Low: 1,200 vehicles

Because the results were positive on the initial 8-mile test section, a next test will be conducted on September 25th extending from Silverthorne to Empire Junction/US 40, a 27-mile section of I-70.  More information will be provided when details are finalized for the next test. As it’s currently scheduled for a Sunday, traffic volumes will be higher and more realistic to when this effort would be deployed.  If results are still positive, CDOT will conduct deploy the next round of rolling speed harmonization when winter driving conditions are in effect.