Economic appraisal models, such as the World Bank's Highway Design and Maintenance Standards Model (HDM-III) and the Road Transport Investment Model (RTIM2) developed by the Transport and Road Research Laboratory in the United Kingdom, are often used to determine optimum maintenance standards that result in minimum life-cycle costs. A simplified method of using concepts built into these models is described that can be used to determine optimum maintenance standards for roads in developing countries. The theory used in developing a graphical method of determining optimum maintenance standards is presented in this paper. This is defined as the maintenance interval required to achieve minimum life-cycle costs. The method uses charts initially derived from results of analyses conducted using either HDM-III or RTIM2. The maintenance intervals obtained from the charts have been compared with a range of maintenance standards modelled using both HDM-III and RTIM2. The results of the comparisons confirm that the graphical method gives optimum maintenance intervals with the minimum life-cycle costs. It is suggested that the method could be applied in developing countries in situations in which expert knowledge of HDM-III or RTIM2 is not locally available. (Author/publisher)
Abstract