Capacity investigation of all-way stop-controlled intersections

Abstract

Depending on traffic conditions, highway functional classification, sight distance, area setting, and other considerations, various traffic controls are used at the location of intersections. One of the essential traffic controls used at intersections is All-Way Stop Control (AWSC) which requires all vehicles to stop before entering the intersection. Proper capacity and headway estimations are essential for AWSC intersections to estimate the capacity. On the other hand, estimating the capacity of these types of intersections was always a challenging and essential task for a transportation engineer. Therefore, this research aims to develop a suitable methodology to estimate the capacity and empirically investigate the AWSC intersections. The literature review of this research identified many existing methodologies for estimating the capacity for unsignalized intersections; however, a few existing studies were for AWSC type of intersection, and others were outdated. Four days of intensive field data collection took place to identify the individual vehicle that entered and exited the intersection--the study site was characterized by single-lane approaches and high levels of vehicular and pedestrian traffic. Using strict protocols, collected data were processed at the individual vehicle. Then the collected data was extracted into a series of spreadsheets for analysis purposes. The method used several variables such as level of conflict, pedestrian activity, and type of movement at the intersection. The study resulted that the total intersection capacity varied between 400 and 1400 vehicles per hour. The study suggested that the wide range of capacity observations is primarily associated with the pedestrian crossing activity at the intersection of interest. Regarding movement type, the right-turn movement was not significantly affected intersection capacity. In contrast, the left-turn movement negatively affected the intersection capacity. Pedestrian traffic at the study site profoundly affected the mean saturation headways for saturation headways. The impact of the type of movement was found notable on the mean saturation headways, and the lowest mean was observed in right-turning vehicles.