Multilane Divided Urban Roads: A Capacity Analysis

Abstract

There are very few passenger cars in India compared to a large proportion of two- and three-wheelers on urban and suburban roadways. Roadside activities generate significant "side friction," which slows down vehicles. As a result, the average speed remains relatively low despite generally acceptable road quality and moderate traffic demand.

Capacity analysis is crucial when assessing existing facilities and calculating the lanes required for new infrastructure. Various factors influence highway capacity, including environmental conditions, traffic control measures, traffic characteristics, and physical road conditions. A significant characteristic of traffic on Indian city roadways is the system's lax regulations and diverse nature. A comprehensive study approach that considers all factors affecting highway capacity is necessary to determine the number of lanes needed to achieve the desired level of service.

This study analyzed ten segments of multilane divided urban highways with varying traffic compositions and physical conditions. The results indicate considerable differences in the Passenger Car Unit (PCU) characteristics among the road sections traffic composition and physical conditions impact capacity. The study found that for every 10% increase in the proportion of two-wheelers in the traffic stream, the capacity of a multilane divided urban road increases by approximately 9%. Conversely, for every 10.2% increase in Non-Motorized Traffic (NMT) in the traffic stream, a section's capacity and free-flow speeds decrease by 2.23% and 7.55%, respectively.