The short answer
A haul road for loaded tippers should be no steeper than 1 in 16, wide enough for two trucks to pass with a margin, shaped so water runs off it, and edged with a berm on any open side. The Coal Mines Regulations put numbers on each of these, and DGMS permissions for mechanised stone quarries commonly carry similar conditions. A well-kept road repays its cost in tyres and cycle time within weeks.
Every tonne a quarry sells travels over the haul road, and so does every litre of diesel and every machine. It is the one asset on the site that all production depends on, and it is commonly the worst-built thing there.
01The figures the regulations use
| Item | Provision |
|---|---|
| Gradient | Not steeper than 1 in 16 |
| Short ramps | Up to 1 in 10 over limited lengths, for tracked machines |
| Width, one-way traffic | Widest vehicle plus 5 m |
| Width, two-way traffic | At least three times the widest vehicle, plus 5 m |
| Berm on an open side | At least as high as the diameter of the largest tyre in use, and at least 1 m wide at the top |
The Metalliferous Mines Regulations have no haul road clause of their own. For a stone quarry these figures arrive as conditions in the DGMS permission, so read the letter for your own mine.
For a tipper 2.5 m wide, that is a one-way road of 7.5 m and a two-way road of 12.5 m. Many quarry roads are half that, which is why loaded and empty trucks stop for each other on every trip.
02Gradient
A grade of 1 in 16 is about 6 per cent. On that slope a loaded tipper climbs steadily in a low gear. Steepen it to 1 in 10 and the same truck is in first gear with the engine at its limit, using far more fuel and moving much more slowly, and coming down it rides its brakes. Long steep ramps are where clutches fail and where runaways happen.
Where the ground forces a steep section, keep it short, straight and followed by a level stretch. Never end a downgrade at a sharp bend or at the hopper.
03The surface
A tipper pushing through loose or rutted ground is doing the same work as one climbing a hill. Engineers call it rolling resistance. A firm, graded surface costs a truck about as much effort as a 2 per cent grade. A soft, rutted one can cost as much as an 8 per cent grade, on the level. That is paid for in fuel, in speed and in tyres cut by loose rock.
- Build the road in layers like any other, on a compacted formation.
- Surface it with 150 to 200 mm of well-graded crushed stone, rolled tight. A quarry has the material.
- Give it a crossfall of 2 to 3 per cent so rain runs to the side instead of along the wheel tracks.
- Cut side drains, and put culverts where water crosses.
- Grade it regularly. A grader for an hour a day keeps a road. A week of neglect loses it.
- Water it in dry weather. Dust is worn-out road leaving the site.
04Curves, junctions and edges
Widen the road on bends, because a long vehicle sweeps a wider path than it does on the straight. Keep sight lines clear at junctions and at the crest of ramps. Along any side with a drop, build a berm of compacted material at least as high as a tipper's wheel. Loose dumped rock does not count, since a truck will push through it.
05What a better road is worth
- Round trip on a rough road at 20 km/h
- 12 min
- Round trip on a maintained road at 30 km/h
- 8 min
- Saved per cycle
- 4 min
- Cycle before, with 10 min loading and tipping
- 22 min
- Cycle after
- 18 min
- More trips per truck
- 22%
The same fleet delivers a fifth more rock to the hopper, or the same rock arrives with one truck in five parked. Tyres are a large part of what a tipper costs to run, and a clean road with no sharp spillage on it adds a great deal to their life. The fleet arithmetic is in how many tippers a job needs.
06The last hundred metres
The approach to the hopper and the area around the loader carry every truck on every cycle and are usually the roughest ground on the site. Level standing at both ends, kept clear of spillage, matters more than any length of road in between.