In this three-part series we are examining how the importance role of engineering in the design, construction, and maintenance of roads is often or not understood, particularly in extractive industries such as mining.

Roads are often placed under the responsibility of mining engineers or supervisors, who are highly intelligent and skilled in their fields, however have a limited understanding of road engineering principles and practices.

Road building is a specialist field that borrows from both civil and geotechnical engineering disciplines as well as relying on skilled, experienced construction supervisors and operators.

Haul roads construction is particularly challenging, as non-standard materials are often all that can be sourced, and the loadings are so severe. Construction without the proper input and monitoring of an engineer is common around the world leading to haul roads being built that impact a mine’s productivity, increases operational costs and can result in accidents.

For example, when haul road ramps are built without engineering planning and oversight, the ramps present an irregular profile, due to the variation of elevation along the road length. This variation ramp generates higher engine temperatures of vehicles, reduces the speed of operation, and reduces the tyre life. At a constant grade ramp location, the operating productivity increases by about 38%.

Another factor that can reduce the productivity is related to the type of material used and compaction of in the wearing course, which some materials have a high rolling resistance that impair the movement of vehicles. Haul roads in a well-maintained condition usually present rolling resistance of 2% to 3%, however roads with inadequate materials and without adequate compaction present rutting that increases rolling resistance from 4% to 8%. This increasingly affects production; according to THOMPSON (2011) the increase of 1% in rolling resistance decreases the truck speed on ramp by 10% and decreases the truck speed on the flat by 26%.

Therefore, materials that make up the haul road pavement need to be selected by suitably qualified and experienced engineers to achieve the required quality. Poor quality materials can compromise productivity and safety, however even with the best materials on hand; poor design and construction can be as equally hazardous.

Engineering expertise coupled with an experienced works supervisor is important to ensure that conditions are understood, to minimise the risk, and to optimise the project outcome given the selection of materials and technologies available. GRT has been developing engineering technologies and processes for haul road pavement management, with solutions from pavement stabilisation and sealing to dust and erosion control, as tools for engineers faced with these challenges.

Please read Part 2 of our series to be released next week where we discuss further the engineering considerations of building and designing required in haul roads in more detail.

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