Higher Mass Limits

Higher Mass Limits (HML) allow particular heavy vehicles to access additional mass entitlements providing:

  • operators of vehicles or combinations running HML on tri-axle groups are accredited under the Mass Management Module of the National Heavy Vehicle Accreditation Scheme (NHVAS), with an accreditation label fitted to the hauling unit
  • vehicles are fitted with certified road friendly suspension
  • vehicles are on an authorised HML route.

HML provides a significant increase in the productivity of road freight transport vehicles.

Road friendly suspension

To be eligible for HML, vehicles must be fitted with certified road friendly suspensions. Road friendly suspension systems reduce the impact of laden axles on road pavements and most bridge structures.

For a suspension system to be considered as road friendly, and therefore eligible for HML, it must be certified to the requirements stipulated under Department of Transport and Regional Services - Vehicle Safety Standards, Vehicle Standards Bulletin 11 – Certification of Road Friendly Suspensions. A list of certified road friendly suspension systems is available from the Commonwealth Department of Infrastructure and Transport.

Higher mass limits set out under the Heavy Vehicle National Law (HVNL)

Below are standard axle mass limit increases for vehicles fitted with certified road friendly suspensions. Before operating under HML, it is strongly recommended that you check the HML transition notice relevant to the jurisdiction/s you will be operating in to ensure that you conform to potential minor variations from the national policy.

Maximum mass per axle group

Type of axle group Maximum mass (tonnes) permitted under GML Maximum mass (tonnes) permitted under HML
Tandem axle group 16.5t 17t
Tri-axle group 20t 22.5t
Single drive axles on buses 9t 10t
Six-tyred tandem axle groups 13t 14t

Intelligence Access Program (IAP)

In Queensland and New South Wales transport operators running HML must participate in the IAP. For more information visit the Intelligence Access Program page.

Authorised routes

When operating at higher mass limits, operators must ensure that the route is authorised for their particular vehicle. Approved HML routes can be found using map layers in our online mapping tool the NHVR Route Planner and on State and territory road transport authority mapping sites.

Access to unauthorised routes

The NHVR coordinates a range of access permit applications from start to finish, liaising directly with road managers (both state and territory road authorities and local government) to manage applications and issue permits. Visit Access applications and forms for permits issued by the NHVR.

See also the Higher Mass Limits fact sheet (PDF, 300KB).