In recent weeks, HVIA members have raised a multitude of issues that are progressively being uncovered as they grapple with the August 1 changes to the Heavy Vehicle National Law (HNVL).
Among those are questions around the new requirements to fit Side Underrun Protection Systems (SUPS) to trailers, which are triggered when the S-dimension of a trailer exceeds 9.5 metres.
HVIA has already raised the issue that the updated HVNL calls for SUPS fitted to trailers in accordance with ADR 106/00, but the ADR itself does not list any category of trailer in its applicability table. That matter remains unresolved, and HVIA will raise it again with the Department of Infrastructure at the next Vehicle Standards Consultative Forum (VSCF) meeting in Canberra in September.
This week, HVIA members uncovered further inconsistencies within the HVNL clauses that concern the fitment of SUPS. Clauses 2 and 2A in Section 4 of the Mass, Dimension and Loading (MDL) regulation specify the SUPS requirements, but exempt refrigerated trailers with S-dimensions exceeding 9.5 metres. However, Clause 5A, which appears later, repeats the same requirement to fit SUPS, but crucially omits the refrigerated trailer exemption.
HVIA raised the matter with the NHVR and the National Transport Commission (NTC), who authored the HVNL changes. Both bodies clarified that Clause 5A was not intended to apply to refrigerated trailers and will be rectified in upcoming HVNL updates.
The following table outlines HVIA’s understanding of requirements to fit SUPS to trailers under the August 1 HVNL changes:
| Trailer S-dimension | Combination length | Trailer type | To SUPS, or not to SUPS? |
| 9.5 metres or less | Up to 19 metres | All trailer types | SUPS not required |
| 9.5 metres or less | From 19 to 20 metres* | All trailer types | SUPS not required |
| Over 9.5 metres | From 19 to 20 metres | All trailer types, excluding refrigerated | SUPS required |
| 9.9 metres or less | Up to 19 metres | Refrigerated | SUPS not required |
| 9.9 metres or less | From 19 to 20 metres* | Refrigerated | SUPS not required |
| Over 9.9 metres | From 19 to 20 metres | Refrigerated | SUPS required |
* The length increase arises from the prime mover being longer
Further, the NTC explains that any trailer built prior to August 1, 2026 is not required to retrofit SUPS, and the regulations were drafted specifically to avoid that outcome.
HVIA sought comments from the NHVR regarding impacts on PBS vehicles and were advised that existing and future PBS vehicles are not required to fit SUPS, unless specified on their PBS approval when granted MDL and ADR exemptions for S-dimensions over 9.5m on semi-trailers.
If members uncover further issues or HVNL inconsistencies, please advise HVIA Chief Technical Officer Adam Ritzinger at a.ritzinger@hvia.asn.au.