, Director, Mechanical Engineering
The Rural Intersection Collision Warning System (i.e., RICWS) has been deployed across the state of Minnesota to provide real-time traffic information to motorists to assist them with identifying sufficient vehicle gaps at thru-STOP intersections. However, since its implementation, a number of complaints have been received from local road users regarding the signs. To identify the human factors issues with the current RICWS sign and to propose safe and efficient alternatives to its use, multiple rounds of usability tests were conducted with Minnesota county engineers and local road users to assist iterative design modifications as well as evaluate the effectiveness of each sign's ability to accurately convey information regarding each of its three states. Three alternative design options were developed and tested along with the original RICWS sign via a driving simulator. A total of 120 participants, including novice teenage drivers (16-18 years old), middle-aged drivers (35-50 years old) and older drivers (65-77 years old), were recruited and then asked to drive through a sequence of rural thru-STOP controlled intersections, with and without the intervention. The objectives were to evaluate the safety effectiveness and efficiency of different RICWS sign options to promote safe gap acceptance at different types of rural intersections (i.e., varying levels of mainstream traffic volume and intersection visibility). The research findings revealed an overall safety benefit of the intervention; however, potential risks were also identified associated with its deployment. It was also observed that drivers' perceptions did not all match their actual driving behaviors.