Test mass and ballast
The test mass is the unladen mass plus ballast, weighed to the stated accuracy and restrained so that it does not move on impact.
Basis. Annex A is normative; the public guidance explains the measurement. The clause number and defined terms are the standard's; the explanation is our own.
Annex A is normative. It is the measurement sheet for the test vehicle. The control ids on this site are our record codes; the citation names the annex and the clauses that supply the facts.
What annex A-02 asks
This control covers the test mass and ballast. The standard defines ballast as the mass added to bring the vehicle within the test mass tolerance. It defines unladen mass as the vehicle without ballast but with manufacturer equipment, engine oil and coolant, and a minimum amount of fuel. Clause 6.1.6 sets the mass measurement accuracy at plus or minus 5 kg per axle for M1 and N1G and plus or minus 50 kg per axle for the other categories. Table 1, which the public preview does not reproduce, is cited for how much ballast may be fixed and how much may be loose. A load bed may be fitted, and the ballast may be held down.
Why it matters
Mass is the largest single number in the rating and the easiest to get wrong. A public weighbridge may be accurate enough for a truck and not for a car. A ballast load that is not restrained can shift on impact and change the centre of gravity. An unladen mass that includes the ballast produces a total that is right by accident and wrong as a record. The buyer who checks the mass record is checking whether the test vehicle was the vehicle the rating claims.
What good looks like
Ask for the weigh ticket, the axle loads, the ballast material and its restraint. Check the arithmetic: unladen mass plus ballast equals the test mass, within the stated tolerance. Check that the ballast is secured in the way the standard permits. Compare the test mass with the threat mass and record the difference.
Evidence an assessor asks for
The reviewer will add the numbers. If the unladen mass already includes the ballast, or the total is outside tolerance, the rating rests on a mass that was not tested.
- Weigh ticket The axle and total masses, the scale used and its calibration
- Mass calculation Unladen mass, ballast and total, with the arithmetic shown
- Ballast record Material, mass, position and restraint method, with photographs
- Tolerance check The measured mass against the required test mass and the permitted tolerance
- Threat comparison The test mass against the mass of the vehicles in the site threat assessment
Where it commonly fails
- The ballast is loose and moves during the impact
- The total mass is taken from the vehicle brochure rather than a weigh ticket
- The mass is outside the tolerance but the report does not say so
- The test mass is 7 200 kg while the site threat is a 3 500 kg vehicle, and the gap is not recorded
What to do before the amendment publishes
Put the weigh ticket and the ballast photograph in the report file. Recalculate the mass before accepting the rating.
Read across
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