NEW MEASUREMENTS FOR SATURATION HEADWAYS AND CRITICAL GAPS AT STOP- CONTROLLED INTERSECTIONS

In January 1993, a comprehensive study of traffic flow characteristics attwo-way and all-way stop controlled intersectio was initiated in the United States through the National Cooperati Highway Research Program. The primary motivation for this study the need for a new set of capacityanalysis procedures for stop-controlled intersections that were based on a comprehensive data base. Phase I of this study has now been completed. During Phase I, traffic operations at seventeen stop-controlled intersections (twelve two-way stop-controlled intersections and f all-way stop-controlled intersections) were videotaped. This pap focuses on the saturation headway and critical gap data that have been collected as part ofthis study. For TWSC intersections, bot critical gap and follow-up timeestimates were made using both the Siegloch and maximum likelihood methods. For AWSC intersections, saturation headway estimates were made and compared with earlier results from Transportation Research Circular 373. (a)