As all quarries and pits have differing geological and structural conditions, so the layout of haul and conveyor routes will present a unique problem at each site and frequently change at various stages in the excavation programme. Haul or conveyor routes are frequently planned to take the excavated materials to the crushers or reception hoppers by the shortest possible routes and the most acceptable gradient. However, following this idealized concept throughout the life of a pit or quarry can lead to a multiplicity of haul roads.
Careful staged planning of haulage systems is essential if loss of reserve through misplaced or redundant routes is to be avoided. Optimum gradient is a controversial subject but in the interests of maximum resource recovery the steepest possible gradient should be sought. Gradients of haul roads in most quarries are designed to be as steep as practicable and grades of 1 : 8 or 1 : 10 are frequently quoted as being suitable for the modern dump-truck fleet. Road widths and corner radii are determined by the size of the equipment in use and the quarry plan needs to take account of the existing and future dump-truck specifications. Whatever the gradient or width, the essential criterion is that haul routes should be well drained and maintained throughout the life of excavation. The plan must allow for adequate protection of both surface and support, and that all necessary equipment and plant is available at the appropriate time. With the increase in use of in-pit crushers and haulage by conveyor to the processing area, there may be a need to include in the quarry plan modifications to the haulage routes. The use of high-angle conveyors requires considerably less width and support and can lead to additional reserve recovery.
In most sand and gravel operations haulage is by conveyor. Wherever possible, the overall plan should ensure that the trunk conveyor is sited on land which will not be excavated and that the number and moves of field conveyors are minimal.