Three objectives are sought: (a) to present a data base for two-way-stop-controlled (twsc) intersections that can be used to investigate the factors that influence delay and capacity, (b) to identify some of the factors that affect delay and capacity at a twsc intersection, and (c) to develop a set of preliminary models to estimate delay and capacity. Traffic flow, delay, and geometric data were collected at nine twsc intersection sites in the pacific northwest encompassing a total of 13 hr of intersection operation. A total of 970 minor-street (subject approach) vehicles were observed and nearly 2, 000 accepted and rejected gaps were identified and recorded. Each sitehas several common characteristics: four approach legs, single lanes on each approach, and a 25-mph speed limit on the major street. Several factors were identified that may influence delay and capacity at a twsc intersection. The time waiting in queue (queue time) is affected by the traffic flow rate on the subject and opposing approaches, whereas the time spent waiting at the stop line (service time) is affected by the traffic flow rate on the conflicting approaches. The capacity of the subject approach is also affected by the flow rate on the conflicting approaches. The size of the accepted gap is affected by the length of time that a vehicle has been delayed, the flow rate on the conflicting approaches, and the directional movement of the subject vehicle. This paper appears in transportation researchrecord no. 1320, Freeway operations, highway capacity, and traffic flow 1991.
Abstract