Evaluation of safety countermeasures at intersections using microscopic simulation.

Abstract

In many jurisdictions, over 40% of all road crashes take place at or near intersections. The need to reduce these crashes has fostered considerable research on the development and evaluation of costeffective countermeasures. Safety engineers have been trying to make decisions affecting safety based on the knowledge extracted from different types of statistical models and/or observational before-after analysis. It is generally recognized that this type of factual knowledge is not easily obtained either statistically or empirically. The use of microscopic traffic simulation over the last two decades has essentially focused on the analysis of system transportation efficiency such as signalized intersections, arterial networks and freeway corridors. The potential of microscopic simulation in traffic safety and traffic conflict analysis was initially recognized by Darzentas et al (1980) and has gained increasing interest in recent years. This paper introduces a micro-level behavioural model to estimate crash potential at intersections for different traffic scenarios and geometric attributes based on deceleration rate to avoid the crash (DRAC) and the maximum available deceleration rate (MADR). The model has been applied to a simple left turn movement for a four-leg unsignalized intersection. For this situation, increases in driver perception and reaction times and reduction in the pavement surface friction were found to increase crash potential significantly. The paper speculates on how the model can be used to provide insights into crash reduction resulting from signalization.