General Mass Limits
General Mass Limits (GML) apply to all heavy vehicles. The GML state the allowable mass for all types of heavy vehicle axle groups unless the vehicle is operating under an accreditation or an exemption under the Heavy Vehicle National Law (HVNL).
Reference Documents
General Mass Limits fact sheet (PDF, 340KB)—detailed information on axle mass limits and axle spacing.
Compliance bulletin 2 – Heavy vehicle mass assessment – Compliance and enforcement bulletin (PDF, 201KB)—information on the methods used to assess compliance with heavy vehicle mass requirements.
1-Tonne Tri-Axle Mass Transfer Allowance (1TMTA)
The 1TMTA provides heavy vehicle operators with flexibility in loading certain heavy vehicle combinations. The 1TMTA allows increased mass on tri-axle groups so that they may be loaded by up to 1 tonne (t) above the normal tri-axle group 20t General Mass Limit (GML) provided any additional mass loaded onto each tri-axle group is offset onto other non-steer axle or axle groups.
1-Tonne Tri-Axle Mass Transfer Allowance fact sheet (PDF, 1MB)
Prescribed dimensions
The prescribed dimension requirements for heavy vehicles are set out under the Heavy Vehicle (Mass, Dimension and Loading) National Regulation.
General Dimension Requirements fact sheet (PDF, 1MB)
Compliance bulletin 3 – Heavy vehicle dimension assessment – Compliance and enforcement bulletin (PDF, 142KB)—information about some of the methods used to assess compliance with heavy vehicle dimension requirements.
Width
The width limit for vehicles is 2.5 metres, excluding:
rear vision mirrors, signalling devices and side-mounted lamps and reflectors
anti-skid devices mounted on wheels, central tyre inflation systems, tyre pressure gauges
permanently fixed webbing-assembly-type devices, such as curtain-side devices, provided that the maximum distance measured across the body including any part of the devices does not exceed 2.55 metres.
Height
The height limit for heavy vehicles is 4.3 metres unless it is a:
vehicle built to carry cattle, horses, pigs or sheep - 4.6 metres
vehicle built with at least 2 decks for carrying vehicles - 4.6 metres
double-decker bus - 4.4 metres
Length
The length of a heavy vehicle is:
for a combination other than a B-double, road train or a car carrier—19 metres
for a B-double—25 metres
for a road train—53.5 metres
for a car carrier —25 metres
for an articulated bus—18 metres
for a bus other than an articulated bus—14.5 metres
for another vehicle—12.5 metres
Trailers - On a semi-trailer or dog trailer the distance from the front articulation point to the rear over hang line must not be more than 9.5 metres and the distance from the front articulation point to the rear of the trailer must not be more than 12.3 metres. The maximum forward projection of a semi-trailer, or anything attached to a semi-trailer must not protrude beyond a 1.9-metre arc from the towing pivot pin (King pin). The articulation point to the rear of a semitrailer may be up to 13.2 metres if the trailer has a distance of not more than 9.5 metres from the front articulation point to the rear overhang line, does not operate in a B-double or road train combination and otherwise complies dimensionally.
Refrigerated van trailers - The distance from the articulation point to the rear of a semi-trailer may be up to 13.6 metres if the trailer is designed and constructed for the positive control of temperature through the use of refrigerated equipment, has a distance from the articulation point to the rear overhang line of no more than 9.9 metres and does not operate in a B-Double or road train combination and otherwise complies dimensionally. Also, the distance from the front articulation point to the rear overhang line of not more than 9.9 metres; and the vehicle must not operate in a B-Double or Road Train combination.
Car carriers - The distance measured at right angles between the rear overhang line of a trailer carrying vehicles on more than one deck and the rear of the rearmost vehicle on the trailer must not exceed 4.9 metres.
Livestock carriers- A trailer built to carry cattle, horses, pigs or sheep on two or more partly or completely overlapping decks must not have more than 12.5 metres of its length available to carry cattle, horses, pigs or sheep. In a B-double built to carry cattle, horses, pigs or sheep, the two semitrailers must not have more than 18.8 metres of their combined length available to carry cattle, horses, pigs or sheep. Note - the length available for the carriage of cattle, horses, pigs or sheep on a trailer is measured from the inside of the front wall or door of the trailer to the inside of the rear wall or door of the trailer, with any intervening partitions disregarded.
Rear overhang and rear overhang line
The rear overhang of a vehicle is the distance between the rear of the vehicle and the rear overhang line of the vehicle.
If a vehicle’s rear axle group comprises of only 1 axle, the rear overhang line is the centre-line of that axle.
If a vehicle’s rear axle group comprises of 2 axles, 1 of which is fitted with twice the number of tyres as the other, the rear overhang line is located at one-third the distance between the 2 axles and is closer to the axle with the greater number of tyres.
If a vehicle’s rear axle group comprises of 3 or more axles, the rear overhang line is the centre-line of the axle group.
If a vehicle’s rear axle group has a steerable axle, that axle is to be disregarded unless:
the group comprises only 1 axle and that axle is a steerable axle; or
all axles in the group are steerable axles.
Rear overhang on rigid trucks - Lesser of 3.7 metres or 60% of wheelbase.
Rear overhang on a semi-trailers and dog trailers - Lesser of 3.7 metres or 60% of ‘S’ dimension.
Rear overhang on a pig trailer - Rear overhang on a pig trailer must not exceed the lesser of the length of the load-carrying area, forward of the rear overhang line or 3.7 metres.
Rear overhang on a bus - Lesser of 3.7 meters or 60% of the wheelbase.
Dimensions relating to specific trailer types
Livestock carriers
A trailer built to carry cattle, horses, pigs or sheep on two or more partly or completely overlapping decks must not have more than 12.5 metres of its length available to carry cattle, horses, pigs or sheep.
In a B-double built to carry cattle, horses, pigs or sheep, the two semi-trailers must not have more than 18.8 metres of their combined length available to carry cattle, horses, pigs or sheep.
Note - the length available for the carriage of cattle, horses, pigs or sheep on a trailer is measured from the inside of the front wall or door of the trailer to the inside of the rear wall or door of the trailer, with any intervening partitions disregarded.
Refrigerated van trailers
The front articulation point to the rear of a semi-trailer may be up to 13.6 metres if the trailer is designed and constructed for the positive control of temperature through the use of refrigerated equipment. Also, the distance from the front articulation point to the rear overhang line of not more than 9.9 metres does not operate in a B-double or road train combination and otherwise complies dimensionally.
Car carriers
The distance measured at right angles between the rear overhang line of a trailer carrying vehicles on more than one deck and the rear of the rearmost vehicle on the trailer must not exceed 4.9 metres.
