Improving safety and traffic operations in urban zones with a high propensity for rear-end collisions at signalized intersections

Abstract

At signalized intersections, rear-end accidents are frequently the predominant accident type. These accidents result from the combination of a lead-vehicle's decelereation and the ineffective response of the following vehicle's driver to this deceleration. The frequency and severity of rear end collisions can be reduced through traffic control and operational improvements. There are different traffic operation strategies for rear-end collision reduction like "Employ multiphase signal operation". "optimize clearance intervals" or "Restrict or eliminate turning maneuvers (including right turns on red)". In practice, the most cost-effective strategy appears to be "Employ Signal Coordination". The first objective of this research report was to use spatial analysis tools to disaggregate Toronto into 76 spatial zones (Toronto is usually divided into 158 zones). The second objective was to rank the 76 zones according to their propensity for rear-end collisions at 4-legged signalized intersections. The third objective was to demonstrate how safety can be improved through signal coordination and progression. The software package Synchro-4.00 was used to recommend improved signal coordination through optimization of cycle lenghts, splits and offsets. The coordination analysis for the 15 intersectins located in the zone with the highest propensity for rear-end collision revealed the following results. 1. Coordination was definitely not recommended for three of the intersections. 2. Coordination was probably not recommended for six of the intersections; and 3. Coordination was definitely recommended for six of the intersections. The coordinatability analysis for the 15 intersections located in the zone with the highest propensity for rear-end collisions was performed on the basis of current cycle length (based on field observations). At the nine intersection where coordination is either definitely not recommended or probably not recommended, current cycle length needs to be optimized.