Discharge Characteristics Analysis of Queued-up Vehicles at Signal-Controlled Intersections Under Heterogeneous Traffic Conditions

Characteristics of discharge vehicle play a significant role in the concept of capacity estimation and designing of a signal-controlled intersection. Highway Capacity Manual (HCM) (Transportation Research Board of the National Academics, 5th edn, Washington, DC, 2000) presents a methodology for analysing signalized intersection considering details of each parameter for a lane-based car-dominated traffic stream, with limited applicability for the mixed traffic conditions. The present study analyses the departure headway characteristics of queued vehicles where a decreasing trend is observed with increase in vehicle position with a saturation headway of 2.05s/veh. The distributions of departure headways are also analysed, and hypothesis result shows that the departure headways at each vehicle position follow a particular log-normal distribution with varying mean and variance. An optimization technique is framed to find out the discharge of vehicles through minimizing the difference between observed flow and ideal flow proposed by HCM (2000). Dynamic passenger car units (PCU) are also estimated through minimizing the Theil's coefficient for accurate estimation of discharge pattern for mixed traffic conditions. The result shows that optimized discharge pattern is close to the ideal one with maximum saturation flow of 1908 PCUs/h (HCM proposed 1900 PCUs/h). A comparative analysis is done between the obtained flow value and flow value proposed by several guidelines and studies to check its suitability for mixed traffic stream.