Benefit

Adaptive signal control at 12 intersections improved average travel time up to 39 percent on Route MO-291.

Experience with adaptive signal systems in Lee's Summit, Missouri.


March 2010
Lee's Summit,Missouri,United States


Summary Information

The Missouri Department of Transportation (MoDOT) installed an InSync adaptive signal control system at 12 intersections on a 2.5 mile section of route Route-291 located between I-470 and US-50 in Lee's Summit, Missouri. The Midwest Research Institute (MRI) collected field data and evaluated corridor performance before and after the system was implemented.

Pre-deployment data were collected in November 2008 and post-deployment data were collected in April and May 2009 (one month after installation) and in September 2009 (five months after installation). Data were collected during weekdays when school was in session to ensure similar travel patterns between studies.

The following data collection activities were performed:
  • A series of travel time runs were conducted to collect travel time, average number of stops, average speed, total delay, stopped time, congested time, and fuel consumption and emissions through the corridor during weekday peak and non-peak periods in both directions of travel.
  • Cross-street traffic was evaluated using the Highway Capacity Manual method for measuring minor-street delays.
  • Traffic volume counts were collected in each direction of travel on the corridor.
  • 12-hour turning movement counts were collected at one intersection.
FINDINGS

The results of the comparison of travel time runs before and after the system was implemented indicate that the adaptive signal system was effective at reducing travel times, delay, emissions, fuel consumption, and the number of stops experienced by drivers in the corridor.

Travel Time and Delay

Overall traffic patterns and traffic volumes remained consistent during the before and after study periods. Although there was a slight increase in delay, up to 12 seconds per vehicle on some minor cross-streets, these delays were easily offset by the much larger decrease in delay observed on the mainline where average travel times decreased by as much as 39 percent for a 2.3 minute reduction in delay depending on the time of day and direction of travel. The number of vehicle stops decreased 17 percent to 95 percent per trip. Average vehicle speeds increased 5 to 10 mi/hr in many time periods.

The range of impacts on travel times was due in part to the configuration of the pre-deployment signal timing plan which already favored the northbound direction of travel, especially during the morning peak. Thus, the southbound direction of travel had potential to realize greater benefits from adaptive signal control.
  • Change in average speed ranged from a 0.2 mi/hr decrease during the AM-peak in the northbound direction, to a 15.5 mi/hr increase (from 25.5 mi/hr to 41 mph) during the morning off-peak in the southbound direction.
  • The average time a vehicle spent traveling at or below 20 mi/hr decreased by a range of 42 to 94 percent (excluding the AM-peak northbound direction of travel).
  • The average time a vehicle spent traveling at or below 30 mi/hr decreased by a range of 36 to 90 percent (excluding the AM-peak northbound direction of travel).
Fuel Consumption and Emissions

Fuel consumption and emissions benefits were limited to the northbound direction of travel during the AM-peak. Impacts on fuel consumption ranged from a 4.5 percent increase to a 21.4 percent decrease. Changes to emissions (HC, CO, and NOx) ranged from a 9 percent increase to a decrease of 50 percent decrease.

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Source

Evaluation of an Adaptive Traffic Signal System: Route 291 in Lee's Summit, Missouri

Author: Hutton,Jessica M.; Courtney D. Bokenkroger; and Melanie M. Meyer

Published By: Missouri DOT

Source Date: March 2010

Other Reference Number: Report No. OR 10-020

URL: http://library.modot.mo.gov/RDT/reports../Ri08026/or10020.pdf

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Typical Deployment Locations

Metropolitan Areas

Keywords

traffic signals, adaptive signals

Benefit ID: 2013-00839