DYNAMIC PCU FOR INTERSECTION CAPACITY ESTIMATION

This paper presents a study to develop the dynamic PCU (Passenger Car Unit) for estimating the capacity of junctions. The most important parameters considered are: (1) traffic composition; (2) the intersection clearing speed for each vehicle type; and (3) vehicle sizes. The formula for estimating the dynamic PCU is derived from: (a) its direct proportionality to the speed ratio; and (b) its inverse proportionality to the space occupancy ratio with respect to a vehicle. In the study, traffic data were collected from two intersections in New Delhi. These were considered to be representative of most of the four-way intersections generally found in Indian urban areas. The data were collected by video cameras, supplemented by physical intersection measurements. It was shown that the dynamic PCU for a vehicle type is controlled mainly by traffic composition. The saturation flow for two different intersections of the same width was found to be nearly the same.