ESTIMATION OF CRITICAL GAP AT UNCONTROLLED INTERSECTIONS

Abstract

The efficiency of the road network mainly depends on the performance of the intersections. India is a country where unsignalised intersections are large in number. Unsignalised intersections are those where gaps in the major stream traffic are utilized by the vehicles in minor stream. Critical gap is the minimum length of time interval between successive major stream vehicles, in which a minor street vehicle can make a maneuver. Critical gap of the driver is used in the estimation of capacity of an intersection and delay corresponding to it. The accuracy of the critical gap estimation determines the accuracy of capacity estimation. There are several methods available in literature to determine the critical gap for a movement. All these methods have been used in present study to determine the critical gap for a vehicle type at two intersections of Hyderabad city. These methods have been derived for uniform traffic conditions and do not consider vehicle class as a variable. A simple method based on the back calculation from the Blunden's entry capacity equation is proposed in the present study to determine the critical gap for a vehicle under mixed traffic situations where major street vehicles enjoy very limited priority.