Effect of PCU Estimation Methods on Capacity of Two-Lane Rural Roads in India: A Case Study

Abstract

The majority of roads in India are two-lane undivided in nature with a supreme heterogeneity in traffic composition. As there is a large variation in dynamic profile of each vehicle, a single unit is essential to estimate the roadway capacity. The Passenger Car Unit (PCU) values of different vehicle categories have significant impact on the estimated roadway capacity. To study this effect, Kolkata-Basanti highway and Howrah-Amta Road, two state highways in the eastern part of India having two lanes each, were selected. Kolkata-Basanti highway connects the rural regions of Sundarban with Kolkata whereas Howrah-Amta Road connects the Amta region with Kona Expressway in the district of Howrah. It has a considerable heterogeneity in traffic with large speed differentials among the vehicles. Greenshield’s linear model is applied to estimate the Capacity where the PCU values are determined by three different methods. These include the static PCU value from IRC 64 (1990), the concept of Dynamic PCU values as proposed by S. Chandra (2004) and the method suggested in Indo-HCM (2017). The analysis shows that there is a significant difference in the roadway capacity estimated using static PCU values from the other two methods. This may be attributed to the fact that the dynamism of the vehicles in the PCU value determination is not considered in the static PCU values listed in IRC 64 (1990).