Development of a Simplified Agency Life-Cycle Costing Tool for Gravel Roads

Abstract

Understanding how roads behave is necessary both for their design and also to make sure that suitable and appropriate maintenance is programmed and carried out effectively. There are many variables that affect road performance, and these differ from place to place. This is true of both paved and unpaved roads. Most countries have a large network of rural unpaved roads that require regular maintenance at relatively high total cost over many years. If the performance of such roads can be improved, especially in whole life terms, their costs can be reduced. Existing decision support tools require extensive data collection before they can be used, which is often beyond the resources available. It was found that two material characteristics, namely plasticity product and grading modulus, had a major effect on the performance of gravel roads, and were found to predict the performance of gravel roads to an acceptable level of accuracy. The results of the study were used to develop a simple life-cycle costing model for gravel roads that allows engineers to improve the performance of gravel roads and to reduce whole life costs. This work is part of the Applied Research on Rural Roads and Transport Services through Community Access Programmes in Africa and Asia (AFCAP2 and AsCAP)