GAV - Common Semi-trailer Combinations

GAV - Common prime mover semi-trailer combinationsThis combination is a prime mover connected to a semitrailer via a fifth wheel coupling.

General access prime mover semitrailer combinations don't require a permit or notice to access road networks; these vehicles have as-of-right access to the network unless a road is signposted.

GAV Dimension Limits

Vehicle dimensions apply to all heavy vehicles. If a GAV exceeds a dimension limit, it becomes a Restricted Access Vehicle (RAV) and will require a notice or permit to access a road or network.

Dimension limits refer to the maximum size and height of a heavy vehicle. The following table summarises general dimension (size) for a prime mover semitrailer combination.

 

Prime mover semitrailer dimensions

Width 2.5 metres
Height 4.3 metres
Length 19 metres
Rear Overhang 3.7 metres or 60% of the wheelbase (whichever is lesser)  

 

GAV Mass Limits

The below tables provide image demonstrations of the:

  • maximum applicable mass for an axle group
  • minimum required axle spacing for the maximum axle group mass limit.
  • maximum total combination mass limit under GML

In some cases, a combination may need to operate at a lesser axle group mass limits (reduced mass) to comply with:

  • the maximum total combination mass limit under GML; or
  • The heavy vehicles GCM

For more details on mass limits, refer to the General Mass Limits webpage

  Prime mover fitted with: Image Max Mass - GML (tonnes) Max Mass - CML (tonnes)
1 a single steer, and single drive axle group towing a single axle trailer Prime mover fitted with a single steer, and single drive axle group towing a single axle trailer 24.0

CML does not apply to single axles

2 a complying steer, and single drive axle group towing a single axle trailer Prime mover fitted with a complying steer, and single drive axle group towing a single axle trailer   CML does not apply to single axles
3 a single steer, and single drive axle group towing a tandem axle trailer Prime mover fitted with a single steer, and single drive axle group towing a tandem axle trailer 31.5 32.0
4 a complying steer, and single drive axle group towing a tandem axle trailer Prime mover fitted with a complying steer, and single drive axle group towing a tandem axle trailer 32.0 32.5
5 a single steer, and single drive axle group towing a triaxle trailer Prime mover fitted with a single steer, and single drive axle group towing a triaxle trailer 35.0 36.0
6 a complying steer, and single drive axle group towing a triaxle trailer a complying steer, and single drive axle group towing a triaxle trailer 39.0 40.0
7 a single steer, and tandem drive axle group towing a single axle trailer a single steer, and tandem drive axle group towing a single axle trailer 31.5

32.0

CML does not apply to single axles

8 a complying steer, and tandem drive axle group towing a single axle trailer a complying steer, and tandem drive axle group towing a single axle trailer 32.0

32.5

CML does not apply to single axles

9 a single steer, and tandem drive axle group towing a tandem axle trailer a single steer, and tandem drive axle group towing a tandem axle trailer 39.0 40.0
10 a complying steer, and tandem drive axle group towing a tandem axle trailer a complying steer, and tandem drive axle group towing a tandem axle trailer 39.5 40.5
11 a single steer, and tandem drive axle group towing a triaxle trailer a single steer, and tandem drive axle group towing a triaxle trailer 42.5 43.5
12 a complying steer, and tandem drive axle group towing a triaxle trailer a complying steer, and tandem drive axle group towing a triaxle trailer 43.0 44.0
13 non-load sharing twin steer, and tandem drive axle group towing a single axle trailer non-load sharing twin steer, and tandem drive axle group towing a single axle trailer 35.5 36.0
14 load sharing twin steer, and tandem drive axle group towing a single axle trailer load sharing twin steer, and tandem drive axle group towing a single axle trailer 36.5 37.0
15 non-load sharing twin steer, and single drive axle group towing a tandem trailer non-load sharing twin steer, and single drive axle group towing a tandem trailer 42.5 43.5
16 load sharing twin steer, and single drive axle group towing a tandem trailer load sharing twin steer, and single drive axle group towing a tandem trailer 42.5 43.5
17 non-load sharing twin steer, and single drive axle group towing a triaxle trailer non-load sharing twin steer, and single drive axle group towing a triaxle trailer 46.5 47.5
18 load sharing twin steer, and single drive axle group towing a triaxle trailer load sharing twin steer, and single drive axle group towing a triaxle trailer 46.5 47.5

 

Note: Combinations operating at Higher Mass Limits (HML) are considered a Restricted Access Vehicle (RAV) and must comply with the relevant state notice or permit conditions.

 

Definitions

Trailer type Relevant position of axle/axle group  
Axle spacing

The spacing between axle groups determines the maximum allowable mass over those axle groups.

Figure 1 shows an example of the axle spacing requirements and mass limits for a rigid truck and dog trailer. There are six checks which all must comply with axle spacings mass limits general table. The spacing between axle groups determines the maximum allowable mass over those axle groups.

Figure 1 - Axle spacing for a four-axle rigid combination

Figure 1 - axle spacing for a four-axle rigid combination

Heavy Vehicle (Mass, Dimension and Loading) National Regulation Schedule 1
Concessional mass limits (CML)  Concessional mass limits are mass exceptions that apply as an exception to the general mass limits. CML applies to certain heavy vehicles and the operator of the CML heavy vehicle must hold NHVAS Mass Management Accreditation and the vehicle must be nominated. Heavy Vehicle (Mass, Dimension and Loading)  National Regulation Schedule 2 
Complying steer vehicle is otherwise known as FUPS

Allowable steer axle mass increase on all Heavy Vehicles greater than 15tonnes.Compliant vehicles may operate with up to an additional 0.5tonnes on the front steer axle (single only). The allowable GVM or GCM can be increased by the additional mass carried on the front steer only.

Where no additional mass is carried on the front steer axle, no GVM or GCM increase is allowed.

FUPS is conditional on the manufacture's ratings for the axles, GVM & GCM

Heavy Vehicle (Mass, Dimension and Loading) National Definitions 
Gross Combination Mass (GCM)  Gross combination mass of the combination Heavy vehicle National Law (HVNL) Definitions 
Gross Vehicle Mass (GVM) The maximum loaded mass the vehicle Heavy vehicle National Law (HVNL) Definitions
General Mass Limits (GML) The heavy vehicle general axle mass limits prescribed in the HVNL that apply to public roads in Australia unless otherwise limited by load restriction signs. Heavy vehicle National Law (HVNL) Definitions
load-sharing suspension system (of an axle group)

means a suspension system:

  1. (a) built to divide the load between the tyres on the group so no tyre carries a mass more than 10% above the mass it would carry if the load were divided equally; and
  2. (b) with effective damping characteristics on all axles of the group
Heavy Vehicle (Mass, Dimension and Loading) National Regulation
Rear overhang    
Semitrailer A typical (conventional) semitrailer has a single axle or an axle group towards the rear of its load carrying surface. Heavy vehicle National Law (HVNL) Definitions
Total combination mass The maximum allowable mass limit for a heavy or combination.  
Tow mass ratio The ratio of the mass of the rigid vehicle to the combined mass of the towed trailer, when all are connected as part of a combination.  
Twinsteer

a hauling that is fitted with a tandem steering axle group.   

The tandem steer axle group is equipped with single tyres to both axles and connected to the same steering column. The axles are spaced at least 1m apart but no more than 2m apart.  

Figure 1 demonstrates the minimum axle spacing requirements of a prime mover fitted with a twinsteer axle group, required to obtain the maximum GML as 11t for load sharing.

Figure 1 - Twinsteer max mass limit spacing

Heavy vehicle National Law (HVNL) Definitions