An Investigation Into the effect of road roughness on Tyre consumption In Uganda

Abstract

In Uganda, the total road network in 2007 was estimated to be 68,800 km classified into national, district, urban and community access road network (African Development Fund, 2007). However, there has been an increas of 103.5% from 2007 to date thereby making a total of 140,000 km in the road network.There is presently an estimated motorized traffic of 8,500 million vehicle-km per year from 3,755 million vehicle-km in 2003, 80% of which is on national roads (Odongo M.M, 2017). However, road maintenance has not been effectively carried out mainly due to incomplete sets of road equipment units at the local governments, ineffectiveness of the equipment, limited funding and stagnation in funding. As a result, a good number of roads are left out without being maintained and hence harbouring functional distresses like rutting, potholes, cracking and corrugations which greatly affect the road user costs like fuel consumption, parts consumption, tyre wear and depreciation. This study aimed at investigating the effect of road roughness on tyre consumption of the different vehicle categories i.e. passenger cars and utilities, large busses and trucks. A large amount of secondary data and information was collected, reviewed and analysed to identify the most relevant tyre consumption model. Then, field observations were carried out so as to determine the condition and extent of the roads by capturing the road defects so as to estimate the road roughness (IRI) in millimeters per kilometer. A total of five paved roads in Kampala district were studied. For paved roads in fair condition (6 m/km IRI), the tyre consumptions of passenger cars, large buses and trucks were 14, 7.5 and 5.4 respectively for every 50,000 km travelled. For paved roads in poor condition (8.5 m/km IRI), passenger cars, large buses and trucks had tyre consumption rates of 38.2, 8.0 and 6.0 respectively. The tyre consumption for passenger cars and utilities proved to be the highest as compared with the other vehicle categories yet they make up about 70% of the total vehicles in the economy. This clearly indicates that a big number of individuals in the country are affected by the tyre consumption rate for this vehicle category. So there’s need to improve in the road network so as to realise less tyre consumption in Uganda.