Microscopic evaluation of traffic safety at signal coordinated intersections: A before–after study

Objective: This research aims to evaluate the safety impacts of signal coordination on signalized intersections and provide a scientific basis to design and improve signal control and management from a traffic safety perspective.Methods: A kernel regression model is adopted to evaluate the safety performance of intersections before and after implementing the signal coordination strategy. By using this statistical method, the authors identify the nonlinear relationship between crash frequency and the crash's spatial location and examine the discrepancy of crash spatial distributions between the coordination and noncoordination conditions at disaggregated levels, such as time of day and crash type. A case study is presented with the use of Michigan crash data (2003–2007).Results: The study finds that the (1) crash distribution on arterials tends to be spatially disperse when the signal coordination is in operation and (2) crash frequency at the approaches of intersections is increased with the use of signal coordination under the following conditions: Nonpeak hours, rear-end and sideswipe crashes, intersections with low speed limits, and both injury and property damage–only crashes.Conclusion: Signal coordination poses safety concerns in addition to its operational benefits for intersections.