Studies on Queue Length and Saturation Flow at Signalized Intersection

Abstract

The most critical element which influences performance of urban road network is the at-grade intersection. To make the urban traffic safe and efficient the most of the at-grade intersections are made signalized. For a signalized intersection design it is very important to know the number of vehicles in a queue of an approach. So in this thesis queue lengths of different approaches of different signalized intersection were determined and how these queue lengths are affected by the green time is studied. Also capacity, operation and design of signalized intersection depend on Passenger Car Unit (PCU) and the saturation flow. As India is a developing country heterogeneous traffic is found in urban roads of India. So to evaluate the overall operation of signalized intersection it is essential to estimate Passenger Car Unit (PCU) and saturation flow of mixed traffic conditions. Analysis of saturation flow is done in this paper.

To do these analysis data were collected from three signalized intersection of Odisha namely IG Park Square (Rourkela), Laxmi Talkies Chowk (Sambalpur) and AG Square (Bhubaneswar). Different methods were used to extract the data. Graph between cumulative arrivals/departures and time is plotted to estimate the queue length and then created relation between these queue lengths and green time. Again to estimate the saturation flow, Passenger Car Unit (PCU) values were calculated. The Passenger Car Unit (PCU) values were calculated using area and speed of different vehicles. The saturation flow values of different approaches were compared with the saturation flow values those are found using Passenger Car Unit (PCU) values of IRC SP-41 and by an equation (S= 525W) present in IRC SP-41.

Queue lengths of different approaches of different intersections were obtained. Also how green time affects the queue length is obtained. The saturation flow values of different approaches estimated using the field Passenger Car Unit (PCU) values were compared with the saturation flow values those are found using Passenger Car Unit (PCU) values of IRC SP-41 and by an equation (S= 525W) present in IRC SP-41. These queue length values and saturation flow values have very significant impact on signalized intersections of urban road of India.