CDOT Announces New Signal Timing Coordination for US 160/US 550 Continuous Flow Intersection North and South

December 10, 2014 - Southwestern Colorado/CDOT Region 5 - Independent analysis shows enhanced safety and efficiency from 9th Street to Santa Rita Drive.

DURANGO – When signal timing changes are implemented to improve the flow of traffic through Durango, the Colorado Department of Transportation contracts with an independent traffic engineering firm to perform several “drive-throughs” to determine whether the changes are successful. In 2012, a firm took traffic counts at the 19 signals along US 160/US 550 from SH 172 to Animas View Drive. Signal timing improvements were made, and before and after drive-throughs were compared to determine the improvements realized. In September of this year the same process was repeated between 9th Street and Santa Rita Drive to measure the results of the recent improvements to two intersections:  US 550 (Camino del Rio) at College Drive and the US 550/US 160 intersection, now a Continuous Flow Intersection (CFI).

The post-construction optimization runs, as these drive-throughs are called, were recently completed by transportation consultant Fehr and Peers. Final data show a decrease in congestion and delay for motorists traveling between 9th Street and Santa Rita Drive along the US 550/US 160 corridor.

“The data they’ve collected and analyzed show an improvement since we’ve made the intersection and traffic signal improvements to the two intersections during our recent project,” CDOT Region 5 Traffic Engineer Mike McVaugh said. “The intersection changes have optimized vehicle travel for motorists and improved safety for pedestrians and bicyclists at both the US 160/US 550 and US 550/College Drive intersections.”

Since the implementation of new signal timing plans in mid-September and completion of the improvements between 9th Street and Santa Rita this summer, the corridor is showing a:

  • Reduced number of stops per vehicle by up to 9% during an average day, and up to 31% during the PM peak hours (which is from 4:00 pm to 6:00 pm).
  • Reduced delay per vehicle by up to 19% during an average day, and up to 31% during the PM peak hours.
  • Reduced emissions by up to 0.7% during an average day, and up to 0.5% during the PM peak hours.*
  • Reduced fuel consumption per vehicle by up to 0.8% during an average day, and up to 0.6% during the PM peak hours.*
  • Improved pedestrian safety and comfort by providing raised refuge medians, pedestrian activated warning signs at unsignalized crossings, and shorter crossing distances with the addition of corner refuge islands.
  • Improved bicyclist safety, comfort and mobility with interconnected bike lanes, green bike lanes, green bike boxes, signing, and bicycle signal detection.

* Because the timing runs were between 9th Street and Santa Rita Drive, a short travel distance, any emissions and fuel consumption improvements cannot be fully recognized.

The new CFI intersection configuration at US 160/US 550 is a first for CDOT and only the second in the state of Colorado. The signal timings were developed using state-of-the-art modeling software that analyzes current traffic volumes and intersection spacing to determine the optimal timing plan to help mainline traffic (along US 550) move efficiently through town while still accommodating side street traffic. Once the modeling is complete, engineers download the individual timing plans to each intersection and then monitor this under actual travel conditions to make final adjustments to the timing. Then, before and after travel runs are compared to show final results.

“With the roadway and signal timing improvements we made we can move the same amount of traffic more effectively to reduce the number of times a motorists gets stopped; when a motorist does get stopped, we have shortened the amount of time he or she has to wait,” McVaugh said. “This does not mean we won’t have periods of traffic congestion in Durango; but it does mean that the green time is optimized at every intersection to best manage the traffic demands at that given time.”

Synchronized or coordinated signal timing is in operation from 6:30 a.m. to 5:45 p.m. on weekdays and weekends. Outside of those periods the signals are set to side street recall, meaning the light changes green for side street traffic only when the vehicle is detected. This is done during low traffic periods, when signal synchronization on US 160/US 550 would cause longer waits to the cars on the side street trying to enter the highway.

“This means that if you’re commuting to work before 6:30 a.m. or after 5:45 p.m., you may not see synchronized signals,” McVaugh explained. “The red lights through town are accommodating detected side street traffic during these lower-traffic times of day.”

Traffic, Emissions and Fuel Consumption Improvements on US 160/US 550 from Santa Rita Drive to 9th Street

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