The choice of standards for African roads

Abstract

The provision of an adequate road system must be regarded as an essential part of a program of economic development. The paper examines what is meant by 'adequate' and adopts as a criterion the concept of lowest total transport cost over the life of the investment. It is suggested that rigidly applied road standards are clearly inappropriate in developing countries and that a program of stage construction should be used supported by a well planned maintenance program. One exception is likely to "be in urban areas where traffic flows are particularly heavy. In this situation the use of road standards established in developed countries is appropriate but modifications due to climate and traffic composition are discussed. Benefits resulting from road improvements, (reductions in operating costs,maintenance costs and time savings) are described and it is suggested that relationship between such costs and road characteristics should provide the basic index, as well as a method of establishing optimum standards. A method using vehicle speeds is discussed in detail.More complex methods are described briefly but the paper points out that whatever approach is adopted it is essential that adequate data are available.It is suggested that all countries should examine how they stand in relation to the data needed to take decisions on road investment and that any deficiencies are rectified. Pavement design must receive attention and account must be taken of the characteristics of local materials and climatic conditions. The analysis of road maintenance problems can only be done on the basis of local studies, extrapolation from one country to another being hazardous. Finally the paper indicates the difficulties of transferring results obtained in one country to another but points out that the basic principles discussed can be utilized by every country in preparing its own policy for road standards.