International Refereed Journal of Engineering and Science (IRJES) ISSN (Online) 2319-183X, (Print) 2319-1821 Volume 3, Issue 5(May 2014), PP.41-49 Passenger Car Unit Values for Urban Mixed Traffic Flow at Signalised Intersections on Two Lane Dual Carriageways in the Tamale Metropolis, Ghana Charles Anum Adams 1 , M. Abdul Muhsin Zambang 2 , Richter Opoku – Boahen 3 1 (Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana) 2 (Department of Civil Engineering, Tamale Polytechnic, Tamale Ghana) 3 (Department of Civil Engineering, Takoradi Polytechnic, Takoradi, Ghana) Abstract:- In many west and east African cities, road traffic mix is characterised by high volumes of two wheeler motorcycles which traverse the roadway without lane discipline. For many years, the Transport Research Laboratory UK (TRL) provided guidelines and parameters for the design of transport facilities based on their research in some countries. In signalised intersection design and traffic operations on roadway facilities, passenger car unit values (PCU) and saturation flows are very important and can vary across cities owing to differences in traffic mix and vehicle characteristics as well as differences in driver behaviour, regulation and enforcement. Local values no matter how crude may be preferred. The traffic mix and performance characteristics on roads in the Tamale metropolis and other northern cities in northern Ghana differ from the other regions due to the high number of motorised two wheeler vehicles in the traffic stream as well as bicycles. Even though this is known, there has not been any research to quantify the Passenger Car Unit values for design. This study aimed to evaluate the local passenger car equivalent unit values which may be used in the design of traffic intersections in order to improve the performance of signalised intersections in Tamale. Two signalised intersections with fixed time control along one of the busiest corridors were studied. Manual counts were used to collect data from three hour video recordings of each intersection under saturation flow conditions played on a laptop computer. The passenger car unit values (PCU) were estimated using multiple regression analysis between the saturation times and vehicle types. PCU values for Motorcycles, Tricycles, Cars and Buses/trucks have been evaluated. It was recommended that a special area should be prepared in front of the signalised intersection stop lines in the metropolis to accommodate the high volumes of motorcycles in the traffic. Keywords:- Northern Ghana, Passenger Car Unit, Saturation Flow, Tamale I. INTRODUCTION For many years, research publications from the overseas centre of the Transport Research Laboratory UK (TRL) formed the basis for design of most transport facilities such as pavements as well as traffic operations on roadway facilities including signalised intersection timing design. Traffic in most cities differ significantly due to differences in traffic mix and vehicle characteristics as well as driver behaviour, regulation and enforcement. Traffic in the Tamale metropolis and other northern cities in Ghana; consist of a high number of motorised two wheeler vehicles in the traffic stream as well as bicycles. In Ghana there are no standardised passenger car unit values (PCU) for design, and research in this area is sparse. This study aimed to evaluate the local passenger car equivalent unit values which may be used in the design and operational analysis of signalised traffic intersections. Vien et al. (2008) states that capacity is the major factor in the design of signalised intersections and saturation flow rate plays an important role in determining the capacity of individual approaches. Traffic operations at signalised intersections would be much easier to analyse if all vehicles in the traffic stream were identical. However, saturation flow is influenced by the proportion and type of vehicles in the traffic stream. Therefore, passenger car equivalent unit values are usually assigned to various categories of vehicle in order to normalise the saturation flow to a common base of passenger car units per hour (pcu/hr). According to Minh and Sano (2003), more than 80% of the total transportation modes in Hanoi, Vietnam, are two-wheelers. In Malaysia, there are approximately 7.5 million registered motorcycles with an increase in motorcycle ownership from 0.13 in 1990 to 0.28 motorcycles per person in 2006. In Korea, authorities have prepared a special area in front of signalised intersection stop lines to accommodate the high volumes of motorcycles. Other countries like Taiwan have introduced a segregated flow concept to improve the performance of traffic mixed with motorcycles (Vien et al., 2008). In the city of Bangalore, India, two-wheelers constitute more than 70% of the total traffic volume, while cars comprise 15%, autos 4% and the remaining www.irjes.com 41 | Page