Development of passenger car unit based on acceleration noise for urban arterials

Abstract

Vehicular traffic in developing countries like India is highly heterogeneous in nature. For effective planning, design, operation and management of highways, determination of traffic volume in a standard unit is a prerequisite. Interactions among vehicles under heterogeneous traffic conditions are highly complex. The passenger car unit (PCU) was therefore developed to represent the amount of impedance caused to the flow of traffic by a vehicle type in comparison with that of a standard vehicle (usually a passenger car). Since urban roads are marked by frequent changes in acceleration–deceleration characteristics, the interaction among various categories of vehicles can be realistically determined using a parameter that represents the change in acceleration/deceleration. A methodology for determining the PCU values of vehicles based on the concept of acceleration noise was developed in this study. The PCU for a study section was determined as the ratio of the variance of acceleration noise of the vehicle under consideration to that of a passenger car. PCU values were determined for four basic categories of vehicles on four-lane divided urban road stretches.