DEVELOPMENT OF PASSENGER CAR EQUIVALENT FOR SIGNALIZED INTERSECTIONS (BASED ON A STUDY CONDUCTED AT SELECTED FOUR SIGLALISED INTERESECTIONS OF HAWASSA CITY, ETHIOPIA

Abstract

The number of passenger cars displaced in a traffic flow by a truck or a bus, under the prevailing roadway and traffic conditions is called Passenger Car Equivalent, Highway Capacity Manual (2010), where estimating it was the basic objective of this dissertation with all other vehicle categories available at signalized intersection of Hawassa City, Ethiopia. Data was collected from four signalized intersections using digital video recorder which is followed by extraction of the time headway. An analytical model was developed to simulate headway values based on total travel time and vehicle type. This model was used to estimate headways of Motorcycle, Auto rickshaw, Passenger cars, Light Duty Vehicle and Heavy Vehicles which are then used to estimated PCE of each vehicle group. Time headway ratio method was chosen for the analysis and estimation of PCE, for it was found to be utilizing such a dynamic characteristic of traffic stream (i.e. headway) which is able to explain driver behavior, roadway surroundings, traffic volume and speed characteristics through a single parameter. The PCE factors of Motorcycle, Auto rickshaw, Light Duty Vehicle and Heavy Vehicle are found to be 0.552, 0.701, 2.004 and 2.967 respectively. The PCE factor value of Motorcycle used by the local standard book, Ethiopian Road Authority, Geometric Design Manual (2013) is less than half of the calculated finding of the study; similarly, for Auto rickshaw the ERA provision is slightly larger than half of the calculated value of this study. The absence of PCE for Light Duty Vehicle and Heavy Vehicle groups and deviation of PCE factors for the remaining vehicle groups from this study result indicates a significant quantity of calculations involving PCE, such as saturation flow rate and thus influences the design of signalized intersections. Finally, it is suggested that the values obtained in this study can be used as a guideline in the design and analysis of signalized intersections in Hawassa City as well as in Ethiopia