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Australian Government: National Measurement InstituteAustralian Government: National Measurement Institute
National Measurement Institute

Weighbridges used for trade

The National Measurement Institute (NMI) seeks to ensure that weighbridge owners and operators and consumers, are aware of the legislative requirements and responsibilities for the use and maintenance of weighbridges. Both consumers and traders benefit from accurate weighing, which can be achieved by adopting and maintaining good measurement practices such as regular maintenance, cleaning and  testing of the weighbridge and ensuring staff are trained in the correct operation and use of the weighbridge.

A weighbridge is defined in the National Measurement Act 1960 as a ‘measuring instrument of one or more platforms that determines the mass of vehicles or livestock and has a measuring capacity of 3 tonnes or more’. A weighbridge used for trade must be of an approved type and must be verified by a servicing licensee or inspector.  The data plate and marks must be clear and legible.  

A weighbridge is deemed “in use for trade” if it is used by a business to determine the measurement of goods (e.g. grain) or services (e.g. cartage or freight) from which a price is calculated and transaction takes place.

A public weighbridge is defined in the National Measurement Act 1960 as a weighbridge that is open for use by or on behalf of the public; or is available for use for a charge.  There are additional requirements if a weighbridge is a public weighbridge and approval is required by NMI to operate as a public weighbridge.

Accuracy and Testing

It is recommended that weighbridges which are in constant and heavy use, be tested for accuracy by a servicing licensee every 12 months. In addition to this it is recommended to place known test weights on the weighbridge at regular intervals to check the accuracy of the measurements.  The weighbridge operator is responsible for ensuring the weighbridge is accurate at all times and that the weighings are conducted in a correct manner.

Responsibilities of a Weighbridge Owner

The owner of a weighbridge has the responsibility to ensure the weighbridge is operating correctly at all times and meets operational requirements, including ensuring the approaches to the weighbridge are compliant and:

  • have a hard, true and durable surface of concrete or another material approved by NMI
  • are in good condition and have not deteriorated
  • have a perimeter that is clearly indicated by painted marks or other approved means
  • be arranged so that drainage from the surface of the approach does not flow into the pit
  • be in the same plane as the platform for a minimum distance of either of the following:
    • If the length of the platform is less than 18 metres – 3 metres
    • If the length of the platform is 18 metres or more – 1 metre.

In addition, the operator should ensure that during operation of the weighbridge:

  • There is a continuous gap between the weighbridge platform and the edge of the weighbridge surround to prevent binding.
  • Stones or other foreign matter are not jammed between the platform and its surrounds as this may cause binding.
  • The weighbridge structure and surrounds are in good condition with no lose bolts, no broken, missing or rusty components.
  • There is no excess water on the platform of the weighbridge during the weighing process; water can accumulate on the platform due to rain or run-off from the vehicle being weighed. Excess water or fluids can affect zero/balance possibly leading to the weighbridge being used in an unjust manner.
  • There is no debris on the weighbridge prior to each weighing.
  • Loose loads, such as sand, are not accumulating in the pit or building up on the platform (affecting balance/zeroing).
  • There is no water or debris under the weighbridge platform.
  • The indicator is showing zero prior to use.

For more information read our Weighbridge Operators Manual.

Weighing Methods

Direct Measurement

Direct measurement is used when the vehicle fits on the platform; it is the most accurate weighing method and must be used whenever possible.

Direct measurement is a single operation, namely the vehicle has all wheels of all axles on one or more platforms of the weighbridge at all times.

End-and-End Measurement

End-and-end measurement is used when it is not possible to determine the mass of a vehicle by direct measurement because the entire vehicle does not fit onto the platform/s. As a result two measurements have to be determined, one for the front and another for the rear of the vehicle.

End-and-end measurement may only be performed on a weighbridge that has suitable approaches and has approval from NMI to perform such measurements.

Axle Load Measurement

Axle load measurements are made to determine the mass supported by separate axles, or groups of axles, of a vehicle.

Research has shown that measurements obtained by direct measurement are more accurate than end-and-end or axle weighing. Inaccurate end-an-end or axle weighing can be caused by a number of factors including uneven approaches, couplings on vehicles etc.

Regulating the Use of Weighbridges

NMI employs trade measurement inspectors throughout Australia. The role of inspectors (PDF 806KB) is:

  • to ensure that all measuring instruments used for trade are verified and used correctly
  • to monitor the verification activities of servicing licensees
  • to check pre-packages for correct packer identification, measurement markings and accurate measure
  • to investigate complaints and resolve problems with trade measurement matters
  • to issue infringement notices or take prosecution action where there has been a breach of the law.

For more Information

The main laws covering trade measurement are the National Measurement Act 1960 and the National Trade Measurement Regulations 2009.

For more information contact 1300 686 664, or use our online form.