Heavy Vehicle Modifications

This is defined as adding or removing a component to/from a heavy vehicle, or making any change that results in the vehicle departing from the manufacturer’s specifications.

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The NHVR Code

Sets out the NHVR framework for the approval of modifications

The NHVR Code of Practice for the Approval of Heavy Vehicle Modifications sets out the National Heavy Vehicle Regulator’s (NHVR) framework for the approval of modifications made to heavy vehicles, and covers a broad range of potential modifications – from the installation of accessories, through to complex changes that have potential major impacts on critical vehicle safety systems.

As a guide, heavy vehicle modifications that need approval are:

Complex modifications based on accepted vehicle engineering practices that can affect the safety of a heavy vehicle if not performed properly
Modifications that are outside the scope of the code of practice that may cause the vehicle to be non-compliant within the heavy vehicle standard – these modifications are usually significant or extensive modifications that have the potential to seriously affect the safety of the vehicle and its operation on the road, or may affect the vehicle design, strength, structural integrity and handling characteristics.

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Heavy vehicle modification codes

NHVR’s modification framework outlines three categories of heavy vehicle modifications – minor, common and complex modifications. Each classification has different assessment and certification requirements.

Minor modifications

Minor modifications as outlined in the NHVR Heavy Vehicle Modification Code are vehicle modifications using vehicle modification techniques that do not require approval – provided the heavy vehicle continues to be within manufacturer’s specifications, and complies with the heavy vehicle standards and regulations.

Minor modifications can include the fitting of optional accessories or the fitting of accessories or components that do not affect the safe operation of the heavy vehicle, such as additional lighting, aerials, air conditioning, alarm systems, plastic shields for lamps and windscreens, and manufacturer’s wheel and tyre options that do not affect the gross vehicle mass or gross combination mass rating of the vehicle.

Common modifications

Common heavy vehicle modifications include regular modifications that are performed and well understood by regulators and industry. These include, but are not limited to coupling installations (fifth wheel, ball or pintle hook coupling type), tray or van body fitment, additional axles or suspension assemblies, or an increase to gross vehicle mass.

Common modifications can be assessed and certified by an appropriately qualified and accredited Approved Vehicle Examiner.

Complex modifications

Complex modifications can affect the safety of a vehicle if not performed properly, and are usually specific modifications that are needed to allow a heavy vehicle to carry out a particular task or function.

Due to their unique nature, complex modifications require assessment and approval by the NHVR on a case-by-case basis, and may need an engineering assessment of the vehicle and modifications to be carried out by a registered engineer to ensure they meet the requirements of the heavy vehicle standards.

Modification approvals, certificates, plates and labels

Must be completed in accordance
with the NHVR Code

Modifications to heavy vehicles must be completed in accordance with the NHVR Code, the specifications and guidance of the original vehicle manufacturer, and any other relevant standards.

When a common or complex heavy vehicle modification is approved by an Approved Vehicle Examiner or State/Territory Transport Authority, an approved modification certificate must be issued and an approved modification plate/label affixed.

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Heavy vehicle modifications
under the Code of Practice

Heavy vehicles modified in accordance with the NHVR Code of Practice maintain the vehicle’s compliance with heavy vehicle standards, and require approval by an Approved Vehicle Examiner. If the vehicle passes inspection, a modification certificate is issued and a modification plate affixed to the vehicle.

Modifications made under the NHVR Code do not require direct approval by the NHVR.

Heavy vehicle modifications not covered by the Code of Practice

Modifications to heavy vehicles that sit outside the NHVR Code of Practice require approval by both the NHVR and an Approved Vehicle Examiner.

These modifications may cause the vehicle to be non-compliant with the heavy vehicle standards, and are usually significant or extensive modifications that have the potential to seriously affect the safety of the vehicle and its operation on the road by affecting the vehicle’s design, strength, structural integrity and handling characteristics.

When the NHVR approves a modification, a Statement of Requirements will be issued detailing how the vehicle modification should be undertaken and any related inspection requirements.

These modifications require approval by an Approved Vehicle Examiner who will issue the modification certificate and ensure a modification plate is affixed to the vehicle if the vehicle passes inspection. The vehicle may require a further inspection subject to particular jurisdiction registration laws.

Heavy Vehicle Modifications

The NHVR Code

Sets out the NHVR framework for the approval of modifications