An infrastructure-based intersection collision-avoidance system (ICAS) designed to provide guidance for left-turning vehicles that have secondary right-of-way and are attempting a turn across the path of opposite-direction traffic is proposed. These types of crashes are most prevalent where a left turn is made from a major road approach. A dominant causal factor in this type of crash is the inability of the left-turning motorist to adequately perceive the required gap for a safe left turn. The proposed ICAS compares the presumed arrival time of the opposite-direction vehicle with the presumed time for a motorist to turn left. Based on this comparison, the system provides guidance to the left-turning motorist in the form of a dynamic sign placed in the same line of sight of opposite-direction traffic, so that motorists will have a "second opinion" to aid in their left-turn decisions. The system is composed of four modules: (a) a left-turn assistance device, (b) left-turn presence detection, (c) opposite-direction detection, and (d) a system processor. The system differentiates between left-turning passenger cars and left-turning heavy vehicles and tailors its guidance appropriately. A non-hardware-specific example of the proposed system at a hypothetical intersection was assessed, along with functional requirements and system limitations.
Abstract