Capacity at Intersections without Traffic Signals

Abstract

Two-way stop control is a form of intersection operation in widespread use. Calculations of the level of service are usually based on gap acceptance theory. In the American Highway Capacity Manual, the influence of pedestrians is considered an impedance factor, whereas in the German guideline the influence of pedestrians and bicyclists has not been considered so far. To close this gap, an alternative calculation method, called the conflict technique, has been developed. This method allows consideration of the influence of nonmotorized road users on the traffic performance of motor vehicles. Moreover, the method provides a significant simplification of the entire theoretical approach. Different modalities of operation, such as a zebra crossing at the entries to an intersection, can be considered, as can the fact that some road users do not comply with the priority rules. It is possible to calculate the capacity for one movement from the minor stream from a single equation. To calibrate the calculation method, traffic at several intersections was observed by video and analyzed for traffic volumes, delays, compliance with priority rules, and other parameters. With these field measurements, the calculation method was calibrated to actual road-user behavior. Comparison of the conventional calculation concept based on gap acceptance and the new conflict technique showed that they provide similar results. In particular, the consideration of pedestrians and limited priority effects is a considerable benefit of the new method.