A German adaptive signal control system (MOTION) improved transit schedule adherence and reduced overall traffic delay by 40 percent.

Evaluating Adaptive Signal Control Techniques (ASCT) in Muenster, Germany.

Date Posted
10/01/2014
Identifier
2014-B00940
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Experiences with Adaptive Signal Control in Germany

Summary Information

This project evaluated the impacts of an adaptive signal control system installed on a busy arterial corridor in Muenster, Germany. The study area included 24 intersections on a 6 km section of the Albersloher Weg corridor where existing pre-timed and traffic actuated control systems were found to be inefficient. To improve traffic flow, Adaptive Signal Control Techniques (ASCT) were implemented using the MOTION (Method for the Optimization of Traffic Signals In On-line controlled Networks) system. Traffic data at a central computer were used to adapt signal behavior to current traffic patterns.
METHODOLOGY

The evaluation was conducted in three stages.
  • Stage-0 included collection of "Before" traffic performance data on the corridor where intersection control was partly pre-timed and partly actuated.
  • Stage-1 included collection of "After-I" traffic data where pre-timed intersection control was coordinated and supplemented with rule based traffic actuation that included rules for bus priority.
  • Stage-2 included collection of "After-II" traffic data where signals were controlled using the MOTION (Method for the Optimization of Traffic Signals In On-line controlled Networks) ASCT-system.

Ten (10) probe vehicles were used to collect traffic performance data on five different routes during morning and afternoon peak periods Tuesday through Thursday. Volunteer test drivers were instructed to obey traffic rules and apply a driving style similar to that of other vehicles on the street. Overall, nearly 1600 probe vehicle trips were evaluated covering a total distance of 1800 km.

GPS trackers and front·side video cameras were used to record vehicle trips and estimate traffic volumes. Average vehicle delay was calculated by comparing travel time between stop bars at intersections against the travel time under the speed limit. Average number of stops was calculated based on number of probe vehicle stops (stop = speed below 2 km/h) on a link divided by the number of probe vehicle trips through the link. Transit data were collected using on-board equipment that enabled bus operators to record the position of each bus continuously. Impacts on pedestrians and cyclists were analyzed by manual observation of crosswalks across the main street.

FINDINGS
  • After the ASCT-system was implemented the average number of stops on the corridor decreased significantly and the average delay decreased by 40 percent. Benefits observed during the project were attributed to the ASCT-system. The conventional methods used to optimize signal control had no significant impacts.
  • Transit buses also benefited from the improved signal control. Transit travel times decreased three to four minutes and reliability increased with sharp reductions in schedule deviations.