Weight is the limit, not volume
With most civil materials, a truck fills up on weight long before it fills up on volume. Sand, crushed rock, scoria, anything dense. The body might look like it has room left, but the axles are already at their legal limit.
That is the part people miss. You picture a truck body and think about how much space is in it. The truck is not thinking about space. It is thinking about weight, because that is what the law and the road care about.
Light material is the opposite. Mulch you can heap to the top of the body, because it weighs almost nothing and you will never hit the weight limit. So mulch genuinely is sold by volume, and that is fine. The trap only bites with heavy material, and it bites because people apply mulch logic to sand.
The maths on a tandem load of granitic sand
Take granitic sand on a tandem. Here are the numbers, and every one of them is public.
| Scenario | Working | Real load |
|---|---|---|
| Best case | 14 t ÷ 1.4 t/m³ | 10 m³ |
| Worst case | 11 t ÷ 1.7 t/m³ | about 6.5 m³ |
So a full, legal tandem load of granitic sand is somewhere between 7 and 10 cubic metres. Call it 9 on an average day.
Now go and look at what a tandem load gets billed as. You will often see 12 cubic metres. Sometimes more.
There are only two ways that happens
If the invoice says 12 cubic metres and a tandem physically cannot carry more than about 10, one of two things is true.
What the gap costs you
The gap looks small per load. It is not small across a job.
Say you bring in 500 cubic metres of granitic sand at $100 a cubic metre, billed in 12 cubic metre loads. That is about 42 loads. If each load was really 9 cubic metres, you paid for 3 cubic metres of air per load. Across 42 loads that is 126 cubic metres you were billed for and never received.
How to check your own invoices
You do not need to take anyone’s word for this. Do it yourself.
The fix is buying on weight
This is why weighbridge dockets matter. A weighbridge docket tells you the actual tonnes that left the quarry. Tonnes do not lie. Cubic metres on a delivery of dense material are an estimate at best, and the place where the story gets told at worst.
At NXT Quarry we bill dense material by weight, off weighbridge dockets you can see. You get what you pay for, and you can prove it. See our crushed rock and sand range and how NXT Control shows every load.