RELATIONSHIPS FOR ESTIMATING VEHICLE OPERATING COSTS IN PAVED AND UNPAVED ROADS IN DEVELOPING COUNTRIES

Research undertaken by the Transport and Road Research Laboratory into the effect of different road standards on the costs of vehicle operation has established robust relationships for a wide range of conditions applicable in developing countries. The paper briefly describes a recent study carried out in the Caribbean to investigate the effect of high road geometry and poor bitumen surfaces on vehicle operating costs and shows how the results obtained have been combined with the results of an earlier TRRL study carried out in Kenya to produce a set of relationships covering both paved and unpaved roads for essentially free flow traffic conditions. In both studies vehicle speed and fuel consumption were investigated experimentally and the other components examined using data obtained from a survey of vehicle operators. All the relationships are expressed in quantities rather than costs and therefore remain valid as long as present vehicle technology remains substantially unchanged. In addition to their use in estimating the cost of operating vehicles of different types on roads of varying standards, the relationships enable the economic benefits of reducing the roughness of the road surface by maintenance or rehabilitation operations to be quantified. (Author/TRRL)