Mass and dimension

Changes to Heavy Vehicle National Law

From mid-2026, prescribed general access mass and vehicle length limits will change under the amended MDL Regulations, following the implementation of the Heavy Vehicle National Law Amendment Bill 2025.

The proposed changes will:

Increase General Mass Limits (GML) to align with the current Concessional Mass Limits (CML)/li>
Expand Euro VI concessions to include road trains.
Increase the length limit for vehicles from 19 metres to 20 metres. (Note: B-doubles are not included in the current regulations but will be considered in future regulatory amendments).
Amend the tow mass ratio and associated conditions for tag trailers.

These changes are still subject to ministerial approval, and until the new legislation and regulations come into effect, the existing MDL rules remain in place.

Find out more in HVNL reform implementation.

Classes of heavy vehicles

The HVNL provides for classes of heavy vehicle as a means of managing access.

Dimension requirements

Dimension requirements for heavy vehicles are set out under the MDL Regulation.

General Access Vehicle

General Access Vehicles do not require a notice or permit to operate on the road network.

Mass limits

Heavy vehicle mass limits are based on the limits set out in the HVNL and MDL Regulation.

Trailer types

Information to assist you in determining your trailer type.

Vehicle charts and fact sheets

Common heavy vehicle combinations used in Australia.

Road Access