Estimation of Critical Gap for through Movement at Four Leg Uncontrolled Intersection

Gap acceptance research is an important study in the estimation of capacity and delay of the specific moment at uncontrolled intersections, and critical gap is one of the primary attributes connected with this study. This attribute is a stochastically distributed value, and it cannot be evaluated directly on the field as it varies with driver, time, intersections, movements and traffic conditions. There are many studies about evaluating the critical gap have been brought out in last two decades. However, the majority of them has been brought out in developed countries where traffic condition is uniform, and rules of priorities, as well as lane regulations, are willingly followed. In India, no one obeys these types of priority rules and consequently generate more complexities on cross-roads. In spite of these conditions in India, very limited studies have been reported in such studies. This paper presents a study of crossing behavior of the driver on uncontrolled intersections. In order to investigate the crossing behavior of the driver, four-legged uncontrolled intersection located in semi-urban area of Ahmedabad in the state of Gujarat was chosen. Video recording system was employed for data gathering, and five video cameras had been utilized concurrently to collect the numerous vehicle movements on different approaches of this intersection. Succeeding, the collected videos are used to extract all the needed parameters like vehicle arrival rate/time, gap/lag time, speed and approaching vehicle types, waiting time, etc. Several existing approaches are employed to estimate the critical gap for through movements from a minor road. Gaps are explained for three different vehicle types (like Car, three wheelers, and two wheelers). A comparison between different existing methods of critical gap determination is carried out, and their critical analysis is performed.