THE KENYA ROAD TRANSPORT INVESTMENT MODEL

A model is described that can be used to aid investment decisions regarding roads in developing countries. It calculates the construction cost of a road and predicts its condition as vehicles traverse it. Having predicted the condition of the road, the model estimates road maintenance and vehicle operating costs for each year. All these costs are then discounted back to the base year and summed over the life of the road to obtain the total cost. All estimates are made in terms of physical quantities, and costs are obtained by applying unit rates to these. The model is flexible and can be used to study the economics of varying stage construction alternatives such as upgrading an earth road to a gravel or paved road at any time during the design life. A case study of the application of the model to a paved road in western Kenya is described. Good agreement is obtained between actual and predicted construction costs. With a first year average daily traffic of about 400, vehicle operating costs over 10 years are two and a half times the cost of initial construction. Road maintenance costs are less than 1 percent of the total transport cost.