A Model for Estimation of Critical Gap and Its Distribution Behaviour at Un Signalised Intersections

Abstract

Traffic congestion on the urban road network is a result of the increase in vehicular traffic as it is characterized by slow speed, longer trip lengths, and longer delays. Unsignalized intersections are provided for low volume traffic flow and its performance is also used to evaluate urban road networks. Delay is considered as the important parameter and evaluation of unsignalized intersections is achieved through gap acceptance behavior. Gap acceptance behavior is an important parameter for the determination of capacity and at unsignalized intersection. This article explicitly presents an overview of the estimation of critical gaps at unsignalized intersections by conventional methods like Raff’s method and maximum likelihood method. The parameters are compared with Indo-HCM for better identification of traffic characteristics. Data are collected through video graphic techniques at two locations in Hyderabad. Traffic parameters like speed, volume, approaching vehicle type, accepted and rejected gaps were extracted. The study has also examined the variables associated with occupancy factor, vehicle type, and socio-demographic features. It is observed that conventional Raff’s method gives accurate results compared with other methods for different types of vehicles. Indo-HCM is also one of the most simplified techniques and gives precise values, and the critical gap values vary at a difference of 0.15 s compared to Raff’s method.