Critical Analysis of Saturation Flow Rate and Affecting parameters

Signalized intersection has the vital importance in the traffic analysis of both arterial and urban roads. Traffic movement from through, right turning, left turning directions meet at a particular junction. These are the areas, which may give rise to conflict or congestion. The capacity of the intersection may vary due to the factors such as lane width, approach grade, categories of vehicle and road users or driving behaviors. The proper planning, design, operation, and management of urban road street network depends upon capacity of the intersection. Saturation Flow rate is one of the important parameter which may affect the capacity of any signalized intersection. It is necessary to design the signal cycle timing as per the required saturated flow of traffic. It is one of the important parameter which is considered while designing of signalized Intersection. Different researchers have given different definitions of saturation flow rate. As per the highway capacity manual saturation flow rate is the equivalent hourly rate at which vehicle can traverse a path in vehicle per hour of green time assuming green signal is provided for 100 % of time. Heterogeneous traffic flow should be considered while determining the saturation flow rate. This paper attempts to study the methodologies used at various locations for determining the saturation flow rate considering varying traffic parameters. It is also tried to identify the suitable methodology for determination of saturated flow rate and related important parameters. Based on the graphical analysis it can be stated that the parameters like headway, PCU, lane width, traffic composition, start -up lost time and Flow plays the important role for determination of saturation flow.