In this first in a series of articles on the principals of haul road construction and maintenance we ask,
WHAT ARE THE BENEFITS OF AN IMPROVED HAUL ROAD INFRASTRUCTURE?
In truck-based hauling systems, the mine haul road network is a critical and vital component of the production process.
As such all the aspects of highway engineering, including road grades, curve elevation, sight distance, stopping distance, adequate drainage, etc., must be followed to facilitate the construction and maintenance of safe and efficient haul roads for the transport of product and equipment to its destination.
Furthermore, underperformance of a haul road will directly impact mine productivity and costs. Operations safety, productivity, and equipment longevity are all dependent on well designed, constructed and maintained haul roads.
With carbon emissions under an ever-increasing spotlight from investors and senior management alike, larger numbers of organisations than ever, across all industries, are targeting a reduction in their operational carbon foot print.
In the context of ‘green fleet’ management this means the efficient operation of diesel vehicles and the reduction of new tyres purchased via optimised haul roads and an effective tyre repair programme.
THE MINE HAUL ROAD IS AN ASSET
The mine haul road is an asset and should, in conjunction with the haul trucks using the road, be designed to deliver a specific level of performance and its routine maintenance managed accordingly. An intelligently designed, constructed and maintained haul network will facilitate safe and efficient mine operation.
The advantages extend to:
- The provision of safer driving conditions and a reduction in traffic hazards.
- Reduced truck operating costs, faster cycle times: higher productivity and lower cost per ton hauled
- Reduced road maintenance costs, less spillage, less water damage due to accumulation, reduced dustiness and longer road service life.
- Less stress on drive train, tyres, frame and suspension: higher asset utilisation and component life, lower life-cycle costs.
- Improved tyre and rim life.
Poor roads pose safety problems for not just haul trucks, but also all road-users.
THE CHALLENGE FOR THE ENGINEERING DESIGN OF A HAUL ROAD
The challenge for the engineering design of a haul road is to optimise the road design to maximise productivity while living within the constraints of providing a safe work environment, an overall mine design, the existing mine topography, and the budget for haul road construction and ongoing maintenance costs.
Without the application of an understanding of the principles of haul road design, the potential of over expenditure on construction and maintenance threatens to increase overall life-cycle costs of a mine, via:
- Over-design and specification, especially in the case of short term, low-volume roads where the effect of rolling resistance, although minimised, does not contribute significantly to reducing total road-user costs across a mine network of roads due to the higher initial construction cost; or
- Under-expenditure on road construction, leading to premature failure; excessive truck operating costs; loss of productivity and, in the case of longer-term, high volume roads, high contributory costs from rolling resistance effects.
- Under-designed roads are often maintenance intensive, so much so that even well built roads appear to perform poorly, due to maintenance being postponed on these roads to accommodate the intensive maintenance requirements of the under-designed roads.
OPTIMISATION OF HAUL ROADS LEADS TO A REDUCED COST PER TON OF MATERIAL HAULED
Truck haulage costs can account for up to 50% of the total operating costs incurred by a surface mine and any savings generated from improved road design and management benefit the mining company directly as reduced cost per ton of material hauled.
Coming next: Factors for consideration when optimising overall haulage costs via haul road construction, design and maintenance.
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