Measurement adjustment

Measurement adjustment is a nationally-agreed process that applies when a vehicle is being measured or weighed for compliance and enforcement purposes.

The Measurement adjustment recognises that a mass or dimension assessment outcome may potentially vary from time to time, due to:

  • the weighing and measuring equipment used
  • the inspection site characteristics
  • measuring methods
  • the conditions under which the measurements are made.

By applying an agreed adjustment to account for these possible variations, the measurement is based on the highest degree of accuracy achievable at any time and provides fairness to the outcome of the measurement process. This means the assessment can legally be relied upon in considering possible enforcement action.

Dimension measurement adjustment (DMA)

DMA relies on two key concepts:

  • Measured dimension (MD) - the reading obtained from the measuring device.
  • Assessed dimension (AD) - the measured dimension minus the relevant DMA.

MD - DMA = AD

The assessed dimension is compared with the dimension limit and breakpoints to determine the severity of any offence that may have occurred.

Mass measurement adjustment (MMA)

MMA relies on two key concepts:

  • Measured mass (MM) - the  reading obtained from the weighing equipment
  • Assessed mass (AM) - the measured mass minus the relevant MMA.

MM - MMA = AM

The assessed mass is compared with the mass limit and breakpoints to determine the severity of any offence that may have occurred.

Inspection site categories

Inspections sites are catergorised based on their physical characteristics and generally fit the following descriptions:

  • Category 1 - a weighbridge or weighing platform and portable scales on a concrete surface.
  • Category 2 - a site that does not fall under Category 1 and that has a bitumen surface.
  • Category 3 - a site that does not fall under Category 1 or Category 2.

Oversize overmass (OSOM) heavy vehicle mass assessment

The MMA is calculated differently for OSOM vehicles.