CAPACITY ANALYSIS OF MULTILANE DIVIDED URBAN ROADS

Abstract

The vehicle fleet on urban and suburban roads in India includes a large proportion of two wheelers and three wheelers. Passenger cars are still few and activities along the side of the road create considerable "side friction" slowing down the traffic. In spite of generally high road standards and moderate traffic demand, the average speed is quite low. Capacity analysis is necessary to have periodic evaluation of the existing facility and to arrive at number of lanes to be provided in a new facility. The factors affecting the capacity of highway are physical conditions, traffic conditions, control conditions and environmental conditions. The main characteristic of traffic on Indian urban roads is its heterogeneous nature and loose structure of regulatory system. It requires an elaborate analysis procedure to arrive at number of lanes at desired level of service by considering all factors affecting highway capacity. Data collected at ten sections of multilane divided urban roads having different physical conditions and varying traffic composition are analyzed in present study. It is found that the PCU factors calculated at different sections of urban roads vary substantially across the sections. Capacity varies with physical conditions and traffic composition. Capacity of a multilane divided urban road increases linearly with increase in the proportion of two-wheelers in traffic stream. It is estimated that capacity of an urban road section increases by approximately 9% for every 10% increase in the proportion of 2-wheeler. Non-motorized traffic (NMT) reduces the capacity and free flow speed of a section by 2.25 % and 7.5% respectively, for every 10 percent NMT in the stream.