Definitions

1. Terminology
2. What does HVO consider a Heavy Vehicle?
3. What is a Restricted Access Vehicle (RAV)?
4. What is a General Access (as of right) Vehicle ?
5. What is an Axle Group?
6. What are the Regulated Dimension Limits?
7. What are the Regulation Mass Limits?
8. What is a Road Train?
9. What is a Turntable/Fifth Wheel?
10. What is a Semi-Trailer?
11. What is a Converter Dolly?
12. What is a Pig Trailer?
13. What is a Dog Trailer?
14. What is a B-Double?
15. What is a Block Truck?
16. What is a Trailer Drawbar?
17. Do I need brake testing certification?
18. Who can I contact for more information?

1. Terminology

• GCM: Gross Combination Mass
• GVM: Gross Vehicle Mass
• ATM: Aggregate Trailer Mass

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2.  What does HVO consider a Heavy Vehicle?

• a vehicle with a GVM exceeding 4.5t;
• a combination that includes a vehicle with a GVM exceeding 4.5t; and
• a load on a vehicle described above.

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3. What is a Restricted Access Vehicle (RAV)?

• is a vehicle that alone or together with any load, exceeds one or more of the following limits:
• a mass limit prescribed in Part 3 of the Road Traffic (Vehicle Standards) Regulations 2002; or
• one of the following dimension limits:
• a width of 2.5m;
• a height of 4.3m;
• a length of 12.5m in the case of a motor vehicle that is not part of a combination; or
• a length of 19m in the case of a combination;
• any other dimension limit specified in the:
• Road Traffic (Vehicle Standards) Regulations 2002 or
• Road Traffic (Vehicle Standards) Rules 2002.

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4. What is a general access (as of right) vehicle?

• is any vehicle that is not a Restricted Access Vehicle (RAV)
• These vehicles generally do not require any permits or exemptions from regulatory requirements

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5. What is an Axle Group?

• is a single axle group, tandem (bogie) axle group, twinsteer axle group, tri-axle group or a quad axle group
• Different axle groups have certain requirements in relation to minimum and maximum axle spacings
• Definitions for each type of axle group are located in Schedule 1 Road Traffic (Vehicle Standards) Regulations 2002

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6. What are the regulation dimension limits?

• Vehicles can be built to various dimensions, which are controlled by the:
• Road Traffic (Vehicle Standards) Regulations 2002;
• Road Traffic (Vehicle Standards) Rules 2002; and
• Australian Design Rules (ADRs)
• Some of the more common dimensions are:
• 4.6m high for vehicle built to carry livestock;
• 2.5m wide for most vehicles;
• 12.5m long for motor vehicles, except an articulated or controlled access bus.
• Regulation dimensions should not be confused when a vehicle requires a permit

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7. What are the regulation mass limits?

• Detailed axle mass limits see Road Traffic (Vehicle Standards) Regulations 2002
• Axle mass limits for the most common axle groups:

• Vehicles must not exceed any manufacturers limit
• The least value should be noted for components such as:
• tyre pressure;
• tyre rating;
• axle rating;
• axle spacing;
• gross vehicle mass (GVM)
• gross trailer mass (GTM)
• aggregate trailer mass (ATM); and
• gross combination mass (GCM)

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8.  What is a Road Train?

Means a combination, except a B-Double, consisting of a motor-vehicle towing at least 2 trailers (counting as a single trailer a converter dolly supporting a semi-trailer).

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9. What is a Turntable/Fifth Wheel?

A device (except the upper rotating element and the king pin, which are parts of a semi trailer) used with a prime mover semi-trailer, or converter dolly

• Device allows quick coupling and uncoupling and provides for articulation
• Turntable is a load-bearing plate that supports vertical and horizontal loads, and is coupled to the semi-trailer"s kingpin and locked into place by a set of jaws

turntable/fifth wheel

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10. What is a Semi-trailer?

• Is a load carrying trailer that has its axle group towards the rear of the trailer
• Its forward connection is by means of a kingpin to either a prime-mover, converter dolly or lead semi-trailer, this arrangement allows up to half of the trailers load to be carried by the prime-mover/convertor dolly/lead semi-trailer

           semi-trailer                     road train with two (2) semi-trailers and one (1) converter dolly

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11. What is a Converter Dolly?

• Is a short trailer with its forward connection by a drawbar, the drawbar normally pivots vertically
• Dollys are only equipped with a turntable
• Dollys are designed to carry some of the load of an attached semi-trailer rather than a load itself
• Road trains are an example of where a converter dolly is used as part of the combination

                             converter dolly

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12. What is a Pig Trailer?

• Is a load carrying trailer that has an axle group near its centre
• Forward connection is by a drawbar, which is normally rigid

                      pig trailer                                                  rigid truck and pig trailer combination

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13. What is a Dog Trailer?

• Is a combination for a fixed or converter dolly with a semi-trailer

                          dog trailer                                                                    triple road train with 2 dog trailers

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14. What is a B-Double?

• Is a prime-mover towing two semi-trailers
• First trailer is a lead semi-trailer ("A trailer"), second is a conventional semi-trailer ("B trailer")
• Lead semi-trailer (A trailer) has a turntable at its rear, this means another semi-trailer can connect without the use of a converter dolly
• B-triple are variations of this concept where three semi-trailers are connected

                  lead semi trailer                                                                         b-double

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15. What is a Block Truck?

• I a haul unit expressly designed to tow other vehicles by means of a drawbar (rather than using a turntable)
• Often used to tow platforms, or a dog trailers in situations where road trains are required to break up (split) at assembly areas

block truck

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16. What is a Trailer Drawbar and it"s length requirements?

• Can be either a single rigid bar or an a-frame which is part of a trailer (except a semi-trailer) connecting the trailer body to a coupling for towing purposes
• Distance between the coupling pivot point on the drawbar of a dog trailer, and the centre of the front axle group or of the front single axle of the trailer, must not be:
• over 5m; and
• under 3m, if the trailer is used in a road train over 19m long
• Distance between the coupling pivot point on a drawbar, and the centre of the axle group or single axle on a trailer with only one axle group or single axle (except a semi-trailer), must not be over 8.5m

drawbar

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17. Do I need brake testing certification?

• Brake testing certification is no longer required by Main Roads (refer to HVO Update 11-2005)
• This requirement has been removed as a pre-requisite for permits because the provisions are specified in the Road Traffic (Vehicle Standards) Rules 2002, Part 9 and Australian Design Rules
• Operators are reminded it is important the vehicle meets these standards to ensure safe operation of the vehicle

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18. Who can I contact for more information?

Heavy vehicle Operations Help Desk

• Tel 9311 8450
• E-mail hvo@mainroads.wa.gov.au
• Fax 9311 8455