EFFECT OF DIRECTIONAL SPLIT AND SLOW MOVING VEHICLES ON CAPACITY OF 2-LANE ROADS

Abstract

The capacity of a traffic facility is the measure of its ability to accommodate stream of moving vehicles. It depends upon traffic, roadway, control and environmental conditions. The capacity analysis is useful in design planning and management of a highway facility. Two lame highways have one lane for use by traffic in each direction and overtaking of slower vehicles requires the use of opposing lane when sight distance and gaps in opposing stream permit. The quality of service is provided by average travel time, percent time delay and capacity utilization. In this study attempt has been made to determine the effect of slow moving vehicles and directional split on the capacity of two lane roads. The data collected at nine sections have been analysed to establish speed-volume relationship and thereby to estimate capacity value. The capacity of highway decreases parabolically with slow moving vehicles and linearly with split. Capacity for 0% slow moving vehicle and for 50-55% directional split in the main direction is 2818 PCU/hr. The capacity of a two lane highway decreases linearly as directional split moves away from even split of 50:50. The capacity with 50:50 directional split and 10.9-15.6% SMV is 2790 PCU/hr.