Road networks are the vital arteries of societies. The need for roads to provide safe and comfortable access and thus contribute to economic sustainability and environmental protection has been increasing with time. Over the years, engineers have become knowledgeable in the optimization of resources for maintaining unsealed roads. Numerous manuals and guidelines have been produced, mostly for developed countries with extensive unsealed networks. Some manuals adopt innovative construction and maintenance methods for the surface layer of unsealed roads. The World Bank has commissioned the development of guidelines for surfacing alternatives for unsealed rural roads to assist countries in making surface selections. The guidelines offer detailed discussion of the following topics: summary of current international experience based on a survey of the literature, case studies and examples, and development of a decision framework for selecting the most appropriate surfacing for given circumstances. The decision framework was developed to offer guidelines and at the same time to remain flexible enough to be applicable for most circumstances. The framework offers a methodology consisting of a three-stage process: Stage 1--evaluation of the need for upgrading on the basis of local environmental and geographic conditions (this stage also allows for overriding political or other aspects); Stage 2--selection of suitable surface types and technologies from the presented list, to result in a short list of options; and Stage 3--suggestion of economic and financial analysis techniques to rank the technically feasible options developed during Stage 2. The guidelines and issues taken into account during the Stage 2 process of deciding on surface technologies are summarized.
Samenvatting