Passenger Car Equivalent Factors in Heterogenous Traffic Environment-are We Using the Right Numbers?

With increasing urbanization, improved transportation technology and an expanding economy, additional roads and highways are built, in an effort to balance roadway capacity and demand. Knowledge of capacity of a road is essential in planning, design and operation of roads. To ascertain estimates of roadway capacity, Passenger Car Equivalent (PCE) factors are vital as they provide mechanism through which vehicles are converted into reference vehicle (i.e. Car). The paper discusses the case of Karachi (A metropolitan city of Pakistan) traffic environment where degree of heterogeneity is significantly high, and based on the collected data set from 12 different urban arterials of Karachi; presents the estimation of PCE factors from four different existing methods. Obtained PCE factors are then compared with each other and with those which are currently used in different traffic studies of Karachi. Significant differences are found among the values of PCE factors from each method.