NEW TRRL ROAD INVESTMENT MODEL FOR DEVELOPING COUNTRIES

Based on the results of a field study carried out in Kenya, a computer model was written to assist engineers and planners in the economic appraisal of new road projects or improvements in developing countries. The model calculates the construction cost of a road and predicts the road condition as time passes. It estimates maintenance costs and vehicle operating costs for each year. These costs are discounted back to the base year and summed over the life of the road to obtain the total cost. The model was programmed in standard FORTRAN. Problems were encountered running this prototype model in developing countries. Some of the difficulties were overcome by publishing the relationships built in the model in a convenient tabular form, thus enabling users in developing countries who do not have access to computers to utilise the model in a manual mode. The model was also reprogrammed to make it easier to use, to enable it to be fitted on to a smaller computer and to utilise the latest field work results carried out by TRRL. (Author/TRRL)