This paper demonstrates the use of traffic micro-simulation modeling for studying the safety impacts of traffic signal treatments and intersection design. It illustrates the methodology and application of this form of modeling using a special incident reduction (IR) function used in signal control in Sweden. The IR-function is designed to mitigate difficult stop-or-go decisions by drivers when caught in the so-called 'dilemma zone' at the onset of amber. A correctly adapted IR-function can greatly enhance the safety performance of signalized intersections. The simulation experiment described in the paper is based on empirical data from a suburban intersection. It was conducted specifically to investigate the effects of the standard IR-function with regard to traffic safety and performance, and to test the boundaries of micro-simulation in relation to safety modeling. Safety effects related to the IR-function were estimated using three proximalsafety indicators: Time-to-Collision, red-light violations and braking rates. The simulation results demonstrated a significant safety effect whenthe IR-function was in operation and a small positive influence on traffic performance. Importantly, this experiment has highlighted the potential for using traffic micro-simulation modeling for traffic safety evaluation in the future.
Abstract