Load, haul & blast Glossary Global
Tonne-kilometre: measuring haulage work
A tonne-kilometre is one tonne moved one kilometre. Multiply tonnes by haul distance to see haulage work that tonnes alone hide; tyres use it per hour.
Definition
Tonne-kilometre
A tonne-kilometre (tkm) is the unit of haulage work equal to one tonne carried a distance of one kilometre, found by multiplying the mass moved by the distance it travels.
Contents 6 sections
Tonnes tell you how much material moved. Tonne-kilometres tell you how much hauling it took. Two pits can load the same tonnes in a shift and ask different amounts of work from the truck fleet, because one face sits 2 km from the tip and the other 4 km.
What a tonne-kilometre means on site
A tonne-kilometre puts mass and distance into one number. Ten tonnes over one kilometre and one tonne over ten kilometres are both 10 tkm. On a haul road that makes it a measure of the work a load represents, separate from how many loads there were.
There are two ways the unit turns up on a mine, and they count different tonnes:
| Use | Mass counted | Distance counted | Expressed as |
|---|---|---|---|
| Haulage work | Payload | Haul distance (state whether loaded leg or round trip) | tkm per shift, per month or per hour |
| Tyre heat rating | Average load on one tyre, laden and empty | Full cycle distance | tkm per hour (TKPH) |
The first is a production figure. The second belongs to tyre selection: Caterpillar describes TKPH as using the product of load and speed as an index of how much heat builds up in the tyre (Caterpillar Performance Handbook 50, p. 29-10, read 25 Sep 2026). The TKPH entry works through that method in full. Keep the two apart: a payload figure fed into a tyre calculation, or a tyre figure quoted as production, gives a wrong answer.
Tonne-kilometre formula
Tonne-kilometres (tkm) = Σ (payload per load, t × haul distance, km)
For a fleet with a steady payload and distance: tkm = payload (t) × distance (km) × number of loads
Haulage rate (tkm/h) = tkm ÷ operating hours
Caterpillar’s shift method for tyres shows the distance side of the calculation: average speed is the round-trip distance in kilometres times the number of trips, divided by total hours in the shift (p. 29-11). The same trip count and distances give you production tonne-kilometres, using payload in place of tyre load.
What changes the tonne-kilometres a truck can deliver
Distance is set by the mine plan. Speed and payload are where a site has room. Thompson’s haul road work shows how much road condition matters: for a large mining truck on a road with a 2% base, each 1% of extra rolling resistance cuts truck speed by about 10% on a ramp and 26% on the flat (Thompson, GSFM, 2011). A slower truck delivers fewer tonne-kilometres per hour on the same road. The rolling resistance entry covers the causes, and the haul truck cycle time guide breaks down where the rest of the hour goes.
Units and conversions
Pay Dirt uses metric tonnes and kilometres. Caterpillar and Michelin also publish imperial ton-mile figures. Caterpillar’s conversion table gives 1 ton-mph as 1.459 tkm/h, which matches a US short ton (0.907 t) moved one mile (1.609 km) (p. 27-8). Michelin converts tyre ratings with TMPH = TKPH × 0.685 (Michelin Technical Data, Earthmover Tires, p. 166), the same factor in reverse.
Common questions
How do you calculate tonne-kilometres for a haul truck?
Multiply the payload of each load by the distance it is carried, then add up the loads. An 80 tonne load hauled 2 km is 160 tkm. Decide first whether you count the loaded leg only or the return too, and keep to it.
Is a tonne-kilometre the same as TKPH?
No. A tonne-kilometre is an amount of work. TKPH is tonne-kilometres per hour, a rate, and in tyre selection it uses the average load on one tyre, not the truck’s payload.
How do tonne-kilometres convert to ton-miles?
Caterpillar’s conversion table gives 1 ton-mph as 1.459 tkm/h, which matches a US short ton moved one mile. Michelin converts tyre ratings the other way: TMPH = TKPH × 0.685.
Sources
- Caterpillar Performance Handbook, Edition 50 (SEBD0351-50), pp. 27-8, 29-10 and 29-11. Caterpillar, June 2022. Read 25 Sep 2026.
- Michelin Technical Data, Earthmover Tires, 2022-23 edition, p. 166. Michelin. Read 25 Sep 2026.
- R.J. Thompson, GSFM: An Integrated Approach to Mine Haul Road Design. Western Australian School of Mines, Curtin University, 2011. Read 25 Sep 2026.
