Author(s): Sarna AC, Jain PK, Chandra G
This paper presents the results of a study to establish capacity norms for selected categories of urban roads in Delhi and Bombay. The main emphasis of the study was the development of simpler techniques for evolving capacity norms, based on observed data. An insight is provided into a new technical approach, the 'enveloping curve technique', for developing suitable capacity norms by adopting an appropriate level of service concept for Indian conditions. 24 locations of road stretches in Delhi and 13 locations in Bombay were selected. Traffic surveys were conducted on all the selected roads for a period of 14 hours, to cover morning and evening peak and off- peak periods. Vehicle types were observed, and speeds were measured. Speed-flow relationships were obtained, capacities were observed, and the results were interpreted, for both divided and undivided roads with two, four, six and eight lanes. Findings include the following: (1) the enveloping curve technique is the best available method for estimating capacities of urban roads for different levels of service; (2) capacities in passenger cars per hour were estimated for different classes of roads in Delhi and Bombay; (3) capacities for similar roads were higher in Bombay than in Delhi; (4) there is scope for improving traffic carrying capacities of urban road sections through such measures as minimising kerbside parking, controlling pedestrian movements and cross traffic, and separating up and down traffic by barriers.