Big Dog Mining

Haul Road Design

Running width, curve widening, superelevation and stopping distance for the biggest truck on the road. The stopping check is the one that matters: a loaded truck on a descent needs far more room than most people expect.

Step 1: The biggest truck on the road

Every dimension below is set by the largest vehicle using the road on a regular schedule, not the average one.

Truck class ?

Truck width auto ?m

Widest point. Road width is a multiple of it.

Vehicle type ?

Articulated units sweep much wider on bends.

Gross vehicle weight auto ?

Loaded. Sets how long the brakes take to bite.

Step 2: The road

Lanes and the tightest bend on the segment you are designing.

Lanes ?

Sets the straight-road multiplier.

Tightest curve radius ?

Inside radius. Blank or 0 for a straight run.

Design speed ?

What trucks really do here.

Grade on descent ?%

Sustained max 8-15%. About 8% is optimum.

Road surface ?

Sets rolling resistance.

Step 3: Braking

The published defaults are Kaufman and Ault's. Change them only with test data.

Tyre-to-road friction ?

Published average is 0.30.

Brake reaction time auto ?s

Set by GVW. Pressure build-up, not the driver.

Driver reaction time ?s

1.5 s is reasonable. Raise it for fatigue, dust or night.

What you get

Every figure traces to a printed page in the working below.

Running width, straight and through the bend
Superelevation for the curve at your design speed
Stopping distance, checked against the 61 m (200 ft) limit
Sight distance you must hold to make that stop
Total resistance for the climb out

running width, m

stopping distance, m

superelevation

Step	Value	Where it comes from

Road cross-section, to scale

Stopping distance

Road width multipliers

Lanes	Factor × widest vehicle

Vehicle on a bend	6 m (20 ft)	45 m (150 ft)	60 m (200 ft)

SME Mining Reference Handbook, 2nd ed., pp. 323-324. The curve figures are a percentage of the straight-road width, by inside radius. Past 60 m (200 ft) the published table stops and no widening is applied here.

Superelevation rates by curve radius and speed

Radius, m

SME Mining Engineering Handbook, p. 963. A blank cell means the combination is not published: that curve is too tight for that speed. The calculator reads conservatively, taking the tighter radius and the higher speed when your values fall between rows.

Maximum rate of superelevation change on tangents

Truck speed, mph	Change per 100 yd of tangent, in./yd

SME Mining Reference Handbook, 2nd ed., p. 326, reproduced with the printed units exactly as published. This one is not computed for you. How the rate converts into a transition length depends on how your own standard applies it, and guessing at an interpretation of the published units is how a design ends up confidently wrong.

Rolling resistance by road surface

Ground surface	Equivalent extra % grade

SME Mining Reference Handbook, 2nd ed., p. 327.

The stopping equation is empirical, and it does not know about heat. It gives a rough estimate only, and it makes no allowance for brake fade: hold the brakes on for long enough and the heat cuts what they can do, which is exactly the situation on a long descent. The 61 m (200 ft) limit comes from the British Columbia Department of Mines and is the reason this calculator flags anything longer. Before you build, get the service brake performance for your actual truck from the manufacturer.

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Terms of use and disclaimer

Estimating aid only. This calculator is an educational tool. It is not an engineering design and it is not a substitute for the judgment of a competent or qualified person.

No warranty. It is provided "as is", without warranty of any kind, express or implied, including any implied warranty of merchantability or fitness for a particular purpose. Equations and constants are cited to their published sources above, but transcription, implementation and the values you enter can all be wrong. Verify every result against the cited source and against your own site conditions before it informs a decision.

Not a statutory document. Nothing produced here is a ground control plan, ventilation plan, blast design, haul road design or hoist design. Those must be prepared, signed and approved under the regulations that apply to your operation. Compliance with MSHA, or with your own jurisdiction's mining regulations, is the operator's responsibility and remains so.

Assumption of risk. You use this tool entirely at your own risk. Mining is hazardous, and errors in ground support, ventilation, blasting or haulage can cause serious injury or death.

Limitation of liability. To the maximum extent permitted by law, Big Dog Mining and its owners, operators and contributors accept no liability for any loss, damage, injury, death, cost or claim, whether direct, indirect, incidental or consequential, arising out of or in connection with the use of this tool or reliance on its output.

Indemnity. By using this calculator you agree to indemnify and hold harmless Big Dog Mining and its owners, operators and contributors against any claim, demand, loss, liability or expense, including reasonable legal fees, arising from your use of it or from any decision taken in reliance on it.

If you do not accept these terms, do not use this calculator.