The overuse of traffic control devices desensitizes drivers and leads to disrespect, especially on low-volume secondary roads with limited enforcement. The maintenance of traffic signs is also a tort liability issue, exacerbated by unnecessary signs. The Federal Highway Administration's (FHWA) Manual on Uniform Traffic Control Devices (MUTCD) and the Institute of Transportation Engineers' Traffic Control Devices Handbook provide guidance for the implementation of stop signs based on expected compliance with right-of-way rules, provision of through traffic flow, context (proximity to other controlled intersections), speed, sight distance, and crash history. The direction to stop is left to engineering judgment and is usually dependent on traffic volume or functional class/continuity of the system. Although currently being considered by the National Committee on Traffic Control Devices, traffic volume itself is not given as a criterion for implementation in the MUTCD. Stop signs have been installed at many locations for various reasons that no longer (or perhaps never) met engineering needs. However, no guidance exists for the removal of stop signs at two-way stop-controlled intersections. The scope of this research is low volume gravel intersections in rural agricultural areas of Iowa, where each of the 99 counties may have as many as 300 or more stop sign pairs. This research investigates the relationship between type of control and independent variables (including traffic volume) to determine the type of warrants that may be used for the removal of stop signs. Overall safety performance is examined as a function of a county overuse factor, developed specifically for this study and based on terrain as a proxy for sight distance and various volume warrant levels. Counties with high levels of rural gravel stop controlled intersection crashes may wish to examine the potential for removing stop control in unnecessary locations to promote compliance with remaining control devices.
Samenvatting