Estimation of Dynamic Passenger Car Unit by Multi Objective Optimization Technique

Abstract

Capacity of an intersection is one of the most significant term to assess the efficiency of the urban road network. In order to bring a heterogeneous traffic stream into a homogeneous one consisting of passenger cars only, the concept of Passenger Car Unit (PCU) factor was introduced. From the past decades several methods were proposed by different researchers across the world to estimate the passenger car unit (PCU) in order to convert the heterogeneous traffic into homogeneous traffic. Among all the existing methods, headway ratio method was used frequently for estimating the PCU values at signalised intersections. Though, headway method have some limitation regarding the non-lane discipline behaviour under the highly mix traffic condition. Most of these proposed methods were found to be based on the homogeneous traffic condition. However, different vehicles categories were found to travel in the same traffic stream while in India, traffic condition is found to be highly heterogeneous in nature. Therefore, the proposed methods cannot be implemented directly under highly heterogamous traffic condition. Still, in India, researchers are using static PCU values which can biased the final outcomes of the study. PCU value can vary with the variation in the traffic conditions (i.e. roadway feature, vehicular characteristics and many more). Therefore, there is a need to use the dynamic passenger car unit (DPCU) instead of static one. Present study proposing a new technique for estimating DPCU at signalized intersections based on multi-objective genetic algorithm (MOGA) technique. One of the objective function of this method is to minimize the variance of the saturation flow. Additionally, second objective is to maximize the overall saturation flow in terns of PCU/h. Another aim of the study is to examine the effect of each vehicle types on the PCU value due to their different static and dynamic characteristics which ultimately affect the PCU value.