• CRADLE TO GRAVE
SMOOTH HAUL ROADS
REQUIRE FOCUS
As a rule, the ability to travel comfortably along a quarry
haul road in a light commercial vehicle at a safe and
acceptable speed is a good indication of a well-maintained
surface. However, this is just one indication, and a host of
other factors need to be considered to ensure a safe and
cost-effective haulage route. These factors include gradients,
drainage and road width design. As a starting point, it
is important to emphasise that haul road maintenance
requires a dedicated focus and must be addressed on a
continual basis as part of the operational cycle since good
roads improve production, extend tyre life and reduce
overall operating costs. The reverse scenario is equally true.
Tyres are a key expenditure item to be preserved for as long
as possible. However, despite this, approximately 80% of all
large tyres fail before wear, due to poor maintenance and
operating practices. This statistic is underscored by a recent
study at a major metal mine, which indicated tyre cuts (45%)
and impact damage (20%) as the largest contributing factors
towards premature tyre failure.
The chief culprit is spillage from off-highway haulage trucks.
It is, therefore, critical that a motor-grader is deployed on
site to continually maintain haulage routes and remove
loose debris.
Poor road maintenance practices also result in an increase
in rolling resistance, defined as the pressure exerted on the
tyres by a road’s riding surface. Typically, for off-highway
trucks running radial-ply tyres, a minimum rolling resistance
of around 1.2% would be expected for a hard and wellmaintained
permanent haul road. However, if this figure
increases by just 5%, the impact becomes disproportionately
greater and could result in up to a 10% decrease in
production, and a 35% increase in production costs.
Essentially, there are three key factors that determine
optimum haul road condition:
• material quality;
• design; and
• maintenance.
It is equally important to note that haul roads begin at the
loading face and end at the dumping point, and maintaining
good floor conditions in both of these areas will definitely
reduce tyre wear and fuel burn costs.
Once a road deteriorates, assuming it was well constructed
in the first place, it takes five times as long to repair it again
to an acceptable condition. In this respect, it is important, in
terms of maintenance, to match the right grader and water
tanker units to the quarry’s haulage route. •
Leon Louw
Well maintained haul roads are key to a smooth operation.
50 • African Mining •May 2020
www. africanmining.co.za