Operating a heavy vehicle

Higher mass limits

Vehicle combinations operating at higher mass limits (HML) must be accredited under the National Heavy Vehicle Accreditation Scheme (NHVAS) mass management module, if a vehicle in the combination or trailer is fitted with a tri-axle group.

Gazette notices

The transitioned notice for Higher Mass Limits for Vehicles fitted with Road Friendly Suspension enables the following vehicles fitted with road-friendly suspension to operate in the HML scheme:

  • rigid trucks fitted with a tandem drive axle group and operated without a trailer
  • articulated vehicles where the prime mover is fitted with a tandem drive axle group and the semi trailer is fitted with either a tandem or tri-axle group
  • buses fitted with a single drive axle or a six-tyred tandem axle group (which includes the drive axle) at the rear.

Operators/drivers of these vehicles must comply with and carry the Gazette Notice within the vehicle.

The operation of Higher Mass Limits (HML) for B-doubles, road trains and vehicle carriers will require operators to comply with the National Heavy Vehicle Regulator (NHVR) national notices, as well as the HML sections in the following transitioned notices and codes of practice which are available on the NHVR's Transitional Notices page.

As operators and drivers are operating under parts of these notices, they are still required to carry the notice within the vehicle.


  • Operation of B-Double Vehicles up to 25 metre in Length
  • Operation of 26 metre B-Double Vehicles
  • Code of Practice for B-Doubles

Road train

  • Operation of Road Train Vehicles in South Australia
  • Code of Practice for Road Trains

Vehicle carrier

Related information


MR 1521 - Higher Mass Limits (HML) fact sheet (725.5 KB PDF)

Contact National Heavy Vehicle Regulator



Phone - 1300 MYNHVR (1300 696 487)
Fax - (07) 3309 8777


PO Box 492
Fortitude Valley QLD 4006

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Page last updated 19 November 2018

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Department of Planning, Transport and Infrastructure
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