Sign Comprehension, Considering Rotation and Location, using Random Gap Simulation for a Cooperative Intersection Collision Avoidance System - Stop Sign Assist: CICAS-SSA Report #4

Crashes at rural thru-stop intersections arise primarily from a driver attempting to cross or enter the mainline traffic stream after failing to recognize an unsafe gap condition.

Because the primary cause of these crashes is not failure to stop, but failure to recognize an unsafe condition, the US DOT FHWA, MnDOT, and the University of Minnesota ITS Institute undertook the CICAS-SSA program. CICAS-SSA uses roadside radar sensors, a computer processor and algorithms to determine unsafe conditions, and an active LED icon based sign to provide timely alerts and warnings which are designed to reduce the frequency of crashes at rural expressway intersections.

The primary goal of this portion of the overall effort was to evaluate several candidate CICAS-SSA concepts in order to identify a single sign that may provide the greatest utility in terms of driver performance and usability at a real-world rural intersection. A secondary goal of the work was to determine the ideal physical characteristics (i.e., location and rotation of a sign relative to drivers) of the candidate CICAS-SSA at a test intersection to maximize comprehension (and subsequent use) of the sign. This report summarizes the results of the work.