The economic viability of upgrading low-volume roads

In many countries, particularly the developing world, a large percentage of the road network is made up of gravel roads. Although such roads are suitable for low traffic volumes, many countries have had rapid increases in traffic levels. This has resulted in high expenditure on maintenance and rehabilitation of gravel roads as well as high costs of vehicle operation. It is therefore desirable to upgrade such roads with bitumen or asphalt pavements at high traffic levels in order to reduce total costs. A computer package incorporating the World Bank Highway Design and Maintenance Standards Model (HDM-111) has been developed to determine the traffic levels at which it becomes economic to upgrade road pavements. Depending on the level of accuracy required, the computer package may be used to give approximate or detailed results. At the simplest operation level, only a few data variables are required to accomplish a quick analysis giving approximate results. A graphical plot of the total costs is displayed on the computer screen showing the cross-over point at which upgrading becomes viable.