TRAFFIC FLOW ANALYSES ON SINGLE AND INTERMEDIATE LANE ROADS

Abstract

Single and intermediate lane roads constitute major portion of road network of state highways, major district roads, other district roads and rural roads and some proportion of national highways. Intermediate lane roads due to reduced width of pavement and complex traffic composition have lesser operating speed and capacity than the two-lane roads. Several studies are reported in literature on two-lane roads in India. But, the studies conducted to understand traffic flow behavior on intermediate and single lane roads are very limited. Prediction and knowledge of capacity is fundamental in design, planning and layout of highways. Among other things, it provides the basis for determining lane width and number of lanes to be provided at any point in a road network with respect to traffic volume and composition. It is a valuable tool for evaluation of the investments needed for future road construction and improvements. The various factors affecting capacity are roadway conditions, traffic conditions and environmental conditions. The traffic stream in India and many other developing countries consists of two distinct categories of vehicles namely, fast moving and slow moving vehicles. The static and dynamic characteristics of these two types of vehicles vary widely. Invariably the same right of way is used for the movement of both type of vehicles. Because of large size of commercial vehicles, heavy load they carry, poor operational performance and wide speed differential, they cause delay to the following vehicles. As a result the capacity of highway is adversely affected. In the present report an attempt has been made to update the capacity values of single and intermediate roads. The data collected at six intermediate lane sections and three single lane sections from different parts of India are analyzed and speed-flow relationships are drawn. It is found that the operating speed of cars have good relation with capacity of single and intermediate lane roads. The relation to determine capacity of single and intermediate lane roads based on operating speed of cars is determined. The concept of stream equivalency factor on single and intermediate lane roads have been introduced. The stream equivalency factor for single and intermediate lane roads based on traffic composition and volume is determined. The results of this study will be very useful in revising the IRC guidelines