ANALYSIS OF MIXED TRAFFIC FLOW THROUGH CONTROLLED INTERSECTION FOR ESTIMATION OF CAPACITY

Abstract

Of all the elements which combine to form the road network, the intersection is one of the most critical in terms of capacity , safety and efficiency . At intersection two or more facilities share the same roadway in terms of space and time resulting in a set of unique opera-tional and design problems . The capacity of a road network especially in the urban areas is largely governed by the capacity of the inter- section . The traffic flow at controlled intersection is of a peculiar type, where traffic on each approach is periodically halted, thus move-ment on a given approach is possible only for a portion of total cycle time. The traffic flow of the type prevailing on Indian roads is hetero-geneous where passenger cars may som etime , tend to constitute a very nominal portion. Almost in all urban intersections different types of vehicles share the same road space without any physical segregation . Enough research has been done in developed countries to study traffic flow behaviour at controlled intersections. The terms density (cars/km) and flow (cars/hour) remain no longer valid for traffic culture prevailing in India and other developing countries as no lane discipline is observed by the vehicles and one lane is occupied by more than one small sized vehicle. In the present study the terms density and flow have been re- defined to suit the mixed traffic situation . An experiment has been designed to collect the data for mixed traffic . The field data was collected from a controlled intersection in New Delhi, representing most of the intersections in urban areas. The relationship between speed (iv) and density have been developed for different approaches of intersection and these relationships are used for capacity calculations. The present study gives only one value of capacity for intersection approach while conventional methods give different values of capacity for different com-position with wide variation from the mean value. Results of the study compare well with the findings of other investigators. It is recommended that further study should be carried out based on extensive data collec-tion taking large number of intersections with wide variation of roadway , traffic and control conditions before generalising the concepts of this study.