Study Details

Study Title: Safety Effect of Arterial Signal Coordination

Authors: Wei and Tarko

Publication Date: JAN, 2011

Abstract: Traffic signals are coordinated mainly with traffic mobility in mind while the impact on safety is not well known. It is not clear how strong this impact is under specific conditions and which coordination solutions increase or reduce this impact. Engineers who set coordinated signals have at their disposal a number of tools to improve traffic mobility along urban streets but no tool to account for safety. This paper studies the impact of arterial signal coordination on the frequency and severity of rear-end and right-angle collisions - the two types of crashes that are prevalent at signalized intersections - the frequency and severity of which are likely to be affected by signal coordination. Multinomial logit models were developed to estimate crash likelihood in 15-minute intervals as well as the severity of crash outcome on arterial intersection approaches. The obtained models were used to investigate the safety impact of signal coordination and other road and traffic variables. The following was determined. (1) Signal coordination can significantly affect crash likelihood and severity. The concentration of vehicle arrivals in the second half of a green phase is associated with significantly lower crash likelihood and severity. (2) Certain components of the traffic flow are most susceptible to crashes. (3) Short distances between intersections and short cycle lengths are associated with a lower risk of crash. (4) The presence of a right-turn bay is associated with a considerable improvement in safety manifested by a lower risk of rear-end and right-angle collisions. The developed models can be used as a tool for evaluating alternative signal coordination plans from the standpoint of safety.

Study Citation: Wei, L. and Tarko, A., "Safety Effect of Arterial Signal Coordination." Presented at the 90th Meeting of the Transportation Research Board, Washington, D.C., (2011).


CMFs Associated With This Study

Category: Intersection geometry

Countermeasure: Presence of right turning lane on arterial with signal coordination

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.06 93.6 3 Stars Rear end All All Urban and suburban
0.32 68.3 2 Stars Angle All All Urban and suburban

Category:Intersection traffic control

Countermeasure: Change number of traffic signal cycles per hour on arterial with signal coordination from X to Y

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
CMF Equation CRF Equation 3 Stars Rear end All All Urban and suburban

Category:Speed management

Countermeasure: Increase speed limit from X to Y mph

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
CMF Equation CRF Equation 3 Stars Rear end All All Urban and suburban
CMF Equation CRF Equation 2 Stars Angle All All Urban and suburban