The safe and optimal operating conditions of haul roads in coal mines is often a feast or famine scenario: the surface is either too wet from excessive watering for dust control purposes or otherwise too dry and dusty from a lack of treatment.Both aspects of haul road safety are problematic, but in this article let’s concentrate on the former – overwatering.
Overwatering can often result in an uncontrolled and unsafe work environment, particularly for truck drivers. It’s a big safety concern that can lead to a range of accidents and incidents on the road network, such as:
- Out of control sliding and skidding
- Corner camber damage (sinking and rutting)
- Collisions on ramps
- Crashes into berms (bund walls)
- Impacts at intersections
- Collisions with the water trucks themselves
Naturally, the problem can be alleviated by haulage trucks adjusting speed to suit the prevalent road conditions, but this will also lead to slower haul cycles, unnecessary delays on the road network and lower productivity. All of these factors ultimately result in reduced profitability.
These problems can be assuaged by haul road designers reducing the number of steep grades, narrow roadways and tight corners particularly on ramps as well as improving berm design (width, height and thickness).
According to Resources Safety and Health Queensland, the design and maintenance of haul roads is integral in surface haulage safety in coal mines.
As they state:
“Over-watering (haul) roads leads to maintenance problems and accidents due to uncontrolled movements of vehicles.” - Mines safety bulletin no. 94 | 22 January 2010 | Version 1
Problems associated with overwatering haul roads in coal mines
As well as the above-mentioned safety risks, overwatering haul roads will:
- Degrade road quality
- Reduce tyre traction
- Increase brake stoppage time
- De-stabilise slopes
- Lead to more maintenance/repairs
- Waste water
- Facilitate erosion
Pooled water can soften road bases, potentially causing further washouts and collapsing fill sections and slopes.
The alternative to overwatering: improving the surfaces of haul roads in coal mines
One of the most expensive repercussions of overwatering haul roads in coal mines is the long-term effects had on the haul road surface.
Excessive water will inevitably wash away the compacted top layer of the wearing course – the fines – and expose the larger, course rocks below.
These larger and invariably sharper rocks can play havoc with haul truck tyres as well as suspension systems which will need replacing sooner.
On top of that, graders must be brought in to resurface the road – at great expense in terms of production rates and man-hours. In addition to this, the fine road material will need to be replaced. It's hard to haul coal while the road is under repair. All in all, not a particularly ‘lean’ process.
The solution for coal mines is to create a more durable road surface that:
- Requires less watering to start with, and
- Is more impervious to the effects of overwatering.
Dust-A-Side recommends the application of DAS Product, a patented emulsion of bitumen in water, to help stabilise haul roads, reduce dust, improve productivity of the network and enhance haul road safety.
Thanks to this proven road management product, the wearing course layer of the haul road is bound together with a bitumen-based binder that reduces the washout of fines and provides an impermeable seal layer which prevents the ingress of water into the sub-layers of the road.
In conjunction with ongoing Dust-A-Side haul road management services, water usage for dust suppression purposes are reduced by 90%+, meaning that the frequency of spraying water to control dust on roads is dramatically reduced.
Less frequent application of water reduces the likelihood of uncontrolled movements and the deterioration of haul roads, therefore making them safer for all road users.
And remember, better quality and dryer haul roads will ultimately increase productivity by increasing haul cycles.
Coal mines will achieve lower operating costs, lower maintenance costs and a lower cost per tonne.
“Watering of untreated roads is the root-cause of 59% of reported uncontrolled vehicle movements (Safety bulletin no.99 (Version 1) 23 August 2010). It follows that eliminating the need to water roads substantially reduces the risk of uncontrolled movements.” - Managing Director, RoadSafety Training Services
Interested in finding more about increasing haul road safety at your coal mine?
Contact us today on 1800 662 387 or click here to arrange an on-site technical consultation and report.
An engineer from the Dust-A-Side team will visit your site (at no cost) to conduct a technical consultation.
From there, our engineers will prepare a preliminary report, detailing recommendations, sand solutions to meet your needs as well as proposed next steps based on the size of your haul road network.
You’ll also receive figures on how soon the mine will break even by engaging our services and how much you will be likely to continue saving on operating costs.