The functional design of surface mine haul roads

The functional design of a pavement relates to the selection of appropriate wearing course materials which optimise the trafficability of a pavement. Trafficability is dictated to a large degree by the choice, application and maintenance of locally available wearing course materials. Poor functional performance results in decreased safety and operational efficiency and inc reasing road and vehicle maintenance requirements.:An optimal functional de sign will include a certain amount and frequency of maintenance (watering, grading etc.) and thus maintenance itself can be planned, scheduled and opt imized within the limits of required road performance and minimum vehicle o perating and road maintenance costs. Since no wearing course material selec tion guidelines, tailored to the specific needs of surface mines, were avai lable, there was the need to identify appropriate Selection guidelines for the range of materials commonly encountered for road building on South Afri can mines. The aim of this paper is to present an overview of the functional design me thod for mine haul roads and, through an analysis and quantification of exi sting wearing course material performance, to recommend appropriate wearing course material selection guidelines. The functional design technique has been applied at a number of mines and is illustrated by an application case study which demonstrates the potential reduction in total transportation o perating costs associated with the optimal functional design.