Oversize or overmass vehicles

Introduction

All vehicles travelling on Northern Territory (NT) roads must comply with the maximum dimensional limits and maximum standard mass limits unless the vehicle has been given an exemption.

Vehicles that are oversize due to loads or equipment must comply with load restraint performance standards.

Read the v64 load restraint information bulletin PDF (362.7 KB).

Permits will generally have conditions of operation on the vehicle. For example, route restrictions.

In the NT, you need a permit for all of the following:

  • a special purpose vehicle that, by construction, exceeds the legal mass and/or dimension limits – eg cranes, drill rigs, plant-type vehicles
  • low loaders and load platforms that are specially designed for the carriage of a large inseparable item or are carrying a large inseparable item
  • vehicles and combinations that transport inseparable loads
  • agricultural machines, agricultural implements or agricultural combinations.

You can also apply or renew to be an oversize load pilot or escort operator.


Dimension limits

This page is about vehicle size limits in the Northern Territory.

It is the responsibility of the vehicle operator to check the relevant legislation.

Width

The overall width of a vehicle including any load must not be more than 2.5m. This excludes any lights, mirrors, reflectors, central tyre inflation systems and signalling devices.

Vehicles with a gross vehicle mass (GVM) of over 3.5 tonne may have mirrors that project an extra 230mm from the widest point of the vehicle, as long as they can fold in to 150mm.

Width and height limits of oversize or overmass vehicles

Height

Maximum vehicle height including any load is 4.3m except for:

  • vehicles designed to carry:
    • livestock can be up to 4.6m high
    • motor vehicles on more than one deck may be up to 4.6m high
  • double-deck buses can be up to 4.4m high.

Overhanging loads

You may carry loads that are longer or wider than the vehicle itself as long as they are within certain limits.

The rear overhang is measured from the centre of the rear axle or axle group to the extreme rear of the vehicle, including any load on the vehicle.

A load must not overhang in a way that is dangerous to people or property even if all dimension and warning requirements have been met - safety is still the main concern.

Any overhang must be contained within the maximum width limit of 2.5m.

Overhang dimensions

(i) Rear overhang is measured from the centre of the rear axle or axle group to the extreme rear of the vehicle including any load on the vehicle.
(ii) Rear overhang must not exceed the lesser of 60% of the wheelbase or 3.7m.

Rear overhang on loaded car carrier trailers, carrying vehicles on more than one deck, may be up to 4.9m, and is measured from the rear overhang line to the rear of the rearmost vehicle carried on the trailer.
(iii) Projecting load to the rear - if a load projects more than 1.2m from the rear of a vehicle, it must carry a warning signal attached to the rear of the load.

In daylight, a warning signal is a brightly coloured flag with sides at least 300mm long.

At night, a warning signal is a red light that can be seen from a distance of at least 200m.

Length

The following images show the maximum length for various vehicles and vehicle combinations. All maximum lengths include any load the vehicle may carry.

A trailer that has:

  • one axle group or single axle to the rear
  • an attachment to a prime mover that results in some of the load being imposed on the prime mover.

Requirements for the semi trailers

Use the following dimension schedules with the image above.

Standard semi trailer - single trailer combination
  1. Any projection forward of the point of articulation must not exceed 1.9m.
  2. Distance from the point of articulation to the rear must not exceed 12.3m.
  3. Rear overhang must not exceed 60% of (D) or 3.7m - whichever is lesser.
  4. Distance from the point of articulation to the rear overhang line must not exceed 9.5m.
14.6m (48 foot) semi trailer - single or last trailer in road train or b-double combination
  1. Any projection forward of the point of articulation must not exceed 1.9m.
  2. Distance from the point of articulation to the rear must not exceed 13.2m.
  3. Rear overhang must not exceed 60% of (D) or 3.7m - whichever is lesser.
  4. Distance from the point of articulation to the rear overhang line must not exceed 9.5m.
Road train or b-double semi trailer
  1. Any projection forward of the point of articulation must not exceed 1.9m.
  2. Distance from the point of articulation to the rear must not exceed 12.3m.
  3. Rear overhang must not exceed 60% of (D) or 3.7m - whichever is lesser.
  4. Distance from the point of articulation to the rear overhang line must not exceed 9.5m.
Refrigerated semi trailer - positive control of temperature with refrigerated equipment - single trailer combination
  1. Any projection forward of the point of articulation must not exceed 1.9m.
  2. Distance from the point of articulation to the rear must not exceed 13.6m.
  3. Rear overhang must not exceed 60% of (D) or 3.7m - whichever is lesser.
  4. Distance from the point of articulation to the rear overhang line must not exceed 9.9m.
Livestock semi trailer

For a livestock trailer with 2 or more overlapping decks (eg. double deck), the available length for the carriage of livestock must not exceed 12.5m measured within the body of the trailer.

A trailer (including a trailer consisting of a semi tailer and converter dolly) that has:

  • one axle group or single axle at the front that's steered by connection to the towing vehicle by a draw bar
  • one axle group or single axle at the rear.

Requirements for the semi and dog trailers

Use the following dimension schedules with the image above.

  1. Any projection forward of the point of articulation must not exceed 1.9m
  2. Distance from the point of articulation to the rear must not exceed 12.3m
  3. Rear overhang must not exceed 60% of (D) or 3.7m, whichever is the lesser
  4. Distance from the point of articulation to the Rear Overhang Line must not exceed 9.5m
  5. Drawbar length is measured from the point of articulation on the tow coupling. Drawbar length not to exceed 5.0m.  If the trailer is used in a road train, drawbar length must not be less than 3.0m.

A dog trailer has an axle group at the front of the trailer that can pivot and is connected to the towing vehicle by a drawbar. There is another axle group at the rear of the trailer.

Dog trailer - length

A pig trailer has one axle group or a single axle near the middle of its load carrying area. It is connected to the towing vehicle by a rigid drawbar.

Pig trailer

Pig trailer

Pig trailer

A b-double is a vehicle combination made up of a prime mover towing 2 semi-trailers.

The length for a b-double truck is measured from the 'king pin' on the forward trailer to the end of the rear trailer as shown above.

B-double truck - length

A road train is a prime mover or rigid truck towing at least 2 trailers, that is not considered a b-double.

Road train

Road train

A car carrier is a truck that is specially designed to carry cars on overlapping decks. Car carriers are not the same as road trains.

Car carrier

Ground clearance

A motor vehicle or combination must have a ground clearance of:

  • at least 100mm within one metre of an axle
  • at least 1/30th of the distance between 2 axles when measured at the midpoint
  • sufficient clearance to allow a vehicle to transverse the peak of a 1:15 gradient.

Requirements for ground clearance

Ground clearance gradient

More information

For more information, read the:

You can also contact MVR by calling 08 8924 7157 or emailing vehiclestandards.mvr@nt.gov.au.


Mass limits

Single axles and single axle groups (one axle or two axles with centre of axle spacing less than 1m)

Description of axle or axle group Mass limit 
Single steer axle on a motor vehicle 6 tonnes
Single axle or single axle group fitted with single tyres with section width of:
(a) less than 375mm
6 tonnes
(b) at least 375mm but less than 450mm 6.7 tonnes
(c) at least 450mm 7 tonnes
Single axle or single axle group fitted with dual tyres on:
(a) a pig trailer
8.5 tonnes
(b) a bus licensed to carry standing passengers 10 tonnes
(c) any other vehicle 9 tonnes

Twin steer axle groups

Description of axle or axle group Mass limit 
Twin steer axle group without a load-sharing suspension system 10 tonnes
Twin steer axle group with a load-sharing suspension system 11 tonnes

Tandem axle groups (at least two axles with the centre of axle spacing at least 1m but not more than 2m)

Description of axle or axle group Mass limit 
Tandem axle group fitted with single tyres with section width of: (a) less than 375mm 11 tonnes
(b) at least 375mm but less than 450mm 13.3 tonnes
(c) at least 450mm 14 tonnes
Tandem axle group fitted with single tyres on one axle and dual tyres on the other axle 13 tonnes
Tandem axle group fitted with dual tyres on:
(a) a pig trailer
15 tonnes
(b) any other vehicle 16.5 tonnes

Tri-axle groups (at least three axles with centre of extreme axle spacing at least 2m but not more than 3.2m)

Description of axle or axle groupMass limit 
Tri-axle group on a vehicle fitted with single tyres with section width of less than 375mm on all axles or single tyres on one or 2 axles and dual tyres on the other axle or axles 15 tonnes
Tri-axle group on a pig trailer with either single tyres with section width of at least 375mm, dual tyres on all axles or a combination of those tyres 18 tonnes
Tri-axle group on a vehicle, other than a pig trailer, with either single tyres with section width of at least 375mm, dual tyres, or a combination of those tyres 20 tonnes

Quad axle groups (at least four axles with centre of extreme axle spacing at least 3.2m but not more than 4.9m)

Description of axle or axle group Mass limit 
Quad-axle group fitted with single tyres with section width of less than 375mm 15 tonnes
Quad-axle group fitted with single tyres with section width of at least 375mm or dual tyres 20 tonnes

Other axle groups

Description of axle or axle groupMass limit 
Any other axle group not specifically referred to in this schedule 20 tonnes

Axle groups fitted with complying road friendly suspension – (each axle group fitted with dual tyres)

Description of axle or axle groupMass limit
Tandem axle group 17 tonnes
Tri-axle group 22.5 tonnes

Apply for an oversize or overmass permit

The assessment criteria for oversize and overmass vehicles is outlined in the permit guidelines PDF (5.0 MB).

The guidelines also outline exemptions that might apply to specific types of vehicles and loads. This includes:

  • B-double overall length exemption
  • 6.5 tonne steer axle mass exemption
  • aggregate spreader box width exemption
  • mechanical tarping and safety harness system width exemption
  • 4.6 metre high semi trailer exemption
  • 14.6 metre (48 foot) semi trailer length exemption.

For 7.1 tonne heavy vehicle steer axle mass exemption, read the information bulletin v75 heavy vehicle steer axle mass PDF (1.3 MB).

To apply for a permit of exemption from the maximum standard dimension and mass limits, read below.

How to apply

To apply, follow these steps:

Step 1. Fill in the oversize or overmass permit application PDF (808.5 KB).

Step 2. Send a copy to the relevant authorities and get authorisations as outlined below.

Step 3. Submit your application and supporting documents by emailing mvr.permits@nt.gov.au or mailing it to:

Chief Transport Inspector
Vehicle Inspection Facility
PO Box 2520
Darwin NT 0801

Step 4. Pay the permit of exemption fee using Visa or MasterCard by calling the MVR office on 1300 654 628.

Get authorisations

Depending on your vehicle type, you may need to get authorisations from authorities including:

  • Telstra or a telecommunications body
  • the Power and Water Corporation (PWC)
  • the Northern Territory (NT) Government department responsible for NT roads
  • the NT Police
  • a local government council
  • a building certifier.

Find out below what authorisation your vehicle type needs for your application.

Seven days before the journey, you must seek approvals from Telstra and email a copy of your completed application to high.loads.telstra@team.telstra.com.

You must also inform Power and Water Corporation (PWC) and email a copy of your completed application to your nearest PWC office:

Ten days before the journey, you must email a copy of the completed application to your nearest PWC office:

Seven days before the journey, you must email a copy of your completed application to the NT Government department responsible for NT roads.

You can do this by emailing roadsdarwin.ntg@nt.gov.au.

At least 28 days before the journey, you must email a copy of your completed form to NT Police.

You can do this by emailing wideloadescorts@pfes.nt.gov.au.

At least seven days before the journey, you must email copy of your completed form to your local council.

You can use the contact details provided on your application.

You must seek the approval of a building certifier.


Recommended routes for oversize loads


Oversize load pilot operator: apply or renew

When piloting an oversize load, you must operate the vehicle according to the permit guidelines for oversize and overmass vehicles PDF (5.0 MB).

Before you apply

If you're applying for the first time, you must have:

  • a training course certificate of attendance
  • a training course certificate of attainment
  • 2 work-related written references
  • a current criminal history check
  • the ability to pilot oversize loads from 3.5m wide up to and including 4.5m wide
  • a current C class driver licence.

If you're applying to be an accredited pilot, you must have:

  • a current C class driver licence
  • a current criminal history check
  • 2 work-related written references
  • the ability to pilot oversize loads from 3.5m wide up to and including 5.5m wide
  • completed the Certificate III in Transport and Logistics with a registered training organisation, proving you can:
    • carry out vehicle inspections
    • pilot or escort oversized and overmass loads
    • use pilot and escort communication
    • co-ordinate breakdowns and emergencies
    • control traffic as a pilot vehicle operator
    • complete a minimum of 10 oversize load piloting jobs (greater than 4.5m wide).

How to apply

To apply, you must follow these steps:

Step 1. Fill in the application or renewal oversize load pilot PDF (749.2 KB).

Step 2. Submit your application and supporting documents by emailing mvr.accreditation@nt.gov.au or by mailing it to:

Chief Transport Inspector
Vehicle Inspection Facility
PO Box 2520
Darwin NT 0801

Step 3. You will be contacted to pay the required fees.


Escort vehicle operator: apply or renew

To apply for an escort vehicle licence, you must have:

  • the ability to escort oversize loads from 3.5m wide up to and including 7.5m wide
  • a current C class driver licence
  • a current criminal history check
  • one work-related written reference
  • an accredited pilot appointment
  • completed the training module 'plan and navigate routes' with a registered training organisation
  • a log book or other proof showing you have piloted:
    • 10 loads in a two pilot situation
    • 5 loads involving an Northern Territory accredited oversize escort operator or authorised officer (police).

How to apply

To apply, you must follow these steps:

Step 1. Fill in the application or renewal escort vehicle operator appointment PDF (749.2 KB).

Step 2. Submit your application and supporting documents by emailing mvr.accreditation@nt.gov.au or by mailing it to:

Chief Transport Inspector
Vehicle Inspection Facility
PO Box 2520
Darwin NT 0801

Step 3. You will be contacted to pay the required fee.