CICAS HF3: Sign Comprehension, Rotation, Location, and Random Gap Simulation Studies

In the United States it is recognized that crashes in rural areas are a cause for concern, especially crashes at rural intersections where inherent speeds may be associated with higher fatality rates (FHWA, 2004). Recent work has shown gap acceptance problems to be the key factor contributing to these crashes (Laberge, et al., 2006) as opposed to stop sign violation (Preston & Storm, 2003). However, the majority of intersection decision-support systems implemented at intersections have not attempted to provide specific information about the nature of available gaps in the approaching traffic or information that supports a driver’s gap acceptance decision. In light of this, to reduce the crash risk at rural stop-controlled intersections, it has been recommended that intersection decision-support systems to assist drivers in responding to safe gaps be developed and deployed (Preston, Storm, Donath, & Shankwitz, 2004). The Cooperative Intersection Collision Avoidance System-Stop Sign Assist (CICAS-SSA) is an infrastructure-based driver support system that is to improve gap acceptance at rural stop-controlled intersections. The SSA system will track vehicle locations on the major road and then display messages to the driver on the minor road. The primary goal of the current work 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 current 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.