Stop control effectiveness as related to volume and sight distance

Abstract

The effectiveness of stop sign control at low volume intersections was assessed utilizing both operational and safety criteria. The dependent variables of violation and compliance rate, conflicts, and accidents were compared in a factorial experimental design to the independent variables of major roadway volume, minor roadway sight distance, rural or urban traffic environment, and type of intersection geometry. Minor roadway volume, signing control, roadway cross-section, geography, and weather were all controlled conditions. The objective of the research was to determine if stop sign control under designated conditions was fulfilling the requirements for application as specified by the Manual on Uniform Traffic Control Devices. This was to be demonstrated by the percentage of observed motorist violations and compliance assuming these measures reflect confirmation of need and respect afforded by the public. The results from 2830 observations at 66 intersections indicates that violation rate decreases with increasing major roadway volume and is significantly high within the 0-1000 ADT level and significantly low above the 5000-6000 ADT level. An interaction effect between major roadway volume and minor roadway sight distance results in a violation rate significantly higher in the unrestricted condition over the restricted condition. No conclusive relationships could be established between violations at low volume intersections in either the rural/urban traffic environment or 3/4-leg intersection geometry type. No correlation was established between violation rate and accidents across all study variables; however, conflict rate was significantly reduced at the upper and lower major roadway volume levels. It was concluded that the operational effectiveness of low volume intersections could be enhanced with no observed safety detriment by the application of no sign control below 1000 ADT major roadway volume, yield sign control between 1000-5000 ADT major roadway volume, and stop sign control or signalization above 5000 ADT, depending on minor roadway volume. These recommendations should be modified based upon adequate sight distance; yet, the determination procedure used in this study seemed insufficient and requires further revision...