How to resolve poor haul road conditions caused by wet weather
The complications associated with the overwatering of haul roads for dust suppression purposes are well documented. These highlight safety issues such as uncontrolled vehicle movements that can have serious consequences for operators and the mine. These hazards are also present during extended periods of wet weather on haul roads (particularly after long spells of dry weather).
With higher than average rainfall expected this summer and autumn, particularly in parts of northern and eastern Australia, the problems that come with extended periods of wet weather and haul roads have become a prominent concern within the industry.
A haul road that is dusty when it is dry can suddenly become extremely slippery and dangerous to navigate when it is wet. When haul roads become too wet, whether from heavy rain or overwatering by water trucks, the risks of uncontrolled movements occurring is significantly increased if the road surface is in bad condition or not properly stabilised.
Uncontrolled movements on haul roads caused by wet weather can include:
- Out of control sliding and skidding
- Collisions on ramps
- Crashes into berms (bund walls)
- Near misses/Impacts at intersections (failure to stop, corrugations, and road pavement destabilisation
- Collisions between trucks and other vehicles on the road network
These incidents are particularly prevalent when haul traffic is required to turn, accelerate and decelerate (typically on corners, switchbacks, at intersections, declines and ramps). That being said, there have been plenty of accidents and incidents on completely flat straight haul roads over the years, making the issue of haul road safety a concern that must be addressed site-wide.
The problems associated with wet roads go beyond safety risks
Other costly repercussions of too much water on haul roads are the effects the water has on the quality of the haul road surface itself.
Excessive water (or constant watering on roads) can wash away the compacted top layer of the wearing course – the fines and pavement material – which exposes the larger, coarser rocks in the sub structures below. Excessive water sitting on roads with poor drainage will also seep through the pavement and into the subbase structures over time causing further road failures.
This erosion in the haul pavement will cause pot-holing and numerous inconsistencies in the surface and exposes larger and sometimes sharper rocks that can cause expensive damage to haul truck tyres, which will have a negative impact on tyre life.
Graders are then brought in to resurface the road – at the further opportunity cost of not building other roads to satisfy production. For particularly significant road failures during and after wet weather, roads will be closed off to the haul fleet until repairs and re-sheeting have been completed.
Along with lowering operating costs and improving productivity, mine managers have the ultimate responsibility to always ensure the safety of workers. This includes providing safe conditions for haul truck drivers on slippery roads.
How to create a durable road surface which is safe in wet weather conditions
To create a haul road surface that remains operational during wet weather, first the mine must focus on building haul roads with adequate crossfall and super-elevation for appropriate drainage.
Secondly, to help protect the road sub structures and shape , the wearing course pavement material should be bound and sealed with an all-weather stabiliser such as a specialised bitumen-emulsion that reduces the washout of fines and provides an impermeable seal layer that prevents the ingress of water into the sub-layers of the road.
At Dust-A-Side, our specially formulated dust control product - DASProduct - is widely used on haul roads and can either be used as a spray-on treatment or established into the wearing course layer of newly constructed haul roads.
DASProduct is a patented emulsion of bitumen in water and works to:
- Stabilise haul roads in order to shed water and prevent flooding and washouts
- Reduce rolling resistance (up to 30%)
- Reduce wheel generated dust (up to 90%)
- Improve braking resistance
- Enhance overall haul road safety and reduce incidents of uncontrolled movements
There are common industry concerns and misconceptions that spraying dust suppressants onto a haul road will actually just make it more slippery. Often what has actually happened is that the wrong type of suppressant technology has been used on the roads (for example common agents such as surfactants sprayed on the roads). These are nothing more than wetting agents with no dust binding properties and can make roads more slippery when applied. Of course, the truth is wet roads are slipperier than dry roads, so driving to conditions is always a critical consideration for operators.
Using dust control agents appropriate for roads such as binders and road stabilisers will improve the wearing course breaking coefficient and reduce frequency of spraying to significantly reduce incidents of uncontrolled movements. An industry leading stabiliser such as DAS Product has been tested to improve braking performance vs non-treated roads in dry or wet conditions.
DASProduct is considered to be an “all-weather” treatment, meaning haul trucks can safely navigate haul roads regardless of how much it has rained or if the treatment was recently applied to the road.
In conjunction with ongoing Dust-A-Side haul road management services, water usage for dust suppression purposes are reduced by 90%+ when DASProduct is applied, meaning that the frequency of spraying water for dust control is dramatically reduced.
Less frequent application of water for dust suppression purposes reduces the likelihood of uncontrolled movements and the deterioration of haul roads, therefore making them safer for all road users, regardless of the weather.
Looking to reduce the risks of uncontrolled haul truck movements at your site? Talk to Dust-A-Side
It’s never too late to implement all weather road solutions for haul road networks, even if many sections of road have already been long established.
Dust-A-Side can treat all road types on a mine site and are experienced haul road managers and maintenance contractors.
To learn more about our range of holistic dust control services, call us on 1800 662 387. Or you can request no obligation consultation by clicking here.