Empirical Study of the Relationship Between Road Surface Conditions and Vehicle Operating Costs in Nigeria

Road surface conditions in Nigeria vary from smooth to severely deteriorated, imposing variable vehicle operating cost burdens on road users that influence economic activity, goods prices, and transport competitiveness. This study empirically examines the relationship between road surface condition and vehicle operating costs for different vehicle classes in Nigeria, developing locally calibrated vehicle operating cost models. Empirical data were collected through instrumented vehicle runs on 18 road sections in Abuja, Lagos, Kano, and Port Harcourt representing a range of PCI values from 10 to 85. Fuel consumption, tyre wear, and maintenance cost data were recorded for cars, minibuses, medium trucks, and heavy trucks over 500 km of test running per vehicle class on each surface condition category. Regression models relating PCI to unit vehicle operating cost per km were calibrated for each vehicle class. Results indicate that fuel consumption on Very Poor roads (PCI < 25) is 34 to 67 percent higher than on Good condition roads (PCI > 70), varying by vehicle class. Tyre wear on Very Poor roads is 2.3 to 3.1 times the rate on Good roads. Aggregate vehicle operating costs on Very Poor roads are estimated at 2.1 to 2.8 times those on Good roads. The study fills a critical empirical gap in Nigeria-specific road user cost data and provides calibrated vehicle operating cost functions for use in road investment economic analysis.

Keywords: vehicle operating costs, road surface condition, pavement condition index, Nigeria, road economics