Chapter 9 of the 1994 update to the 1985 "Highway Capacity Manual" presents the operational and planning analysis of signalized intersections. The methodology for saturation flow rate estimation does not consider all elements of the interaction between turning vehicles and pedestrians and/or bicycles. This paper describes this interaction using a conflict zone occupancy approach. A conflict zone is a portion of an intersection, typically in the crosswalk, where pedestrians and vehicles compete for space. Conflict zone occupancy, defined as the fraction of the effective green period during which pedestrians or bicycles occupy a conflict zone, provides the basis for a rational adjustment to saturation flow. This paper describes the relationship between the number of net lanes (the number of departure lanes divided by the number of turn lanes) and the effect of occupancy on saturation flow. Armed with pedestrian and bicycle volumes, traffic engineers can use the procedure contained herein to compute the effect of pedestrians and bicycles on the saturation flow of vehicles turning from either one-way or two-way streets. (A)
Samenvatting