On top of the final Consultation Paper for the revised Directional Stability Under Braking (DSUB) Technical Standard, the National Heavy Vehicle Regulator (NHVR) has also released a Technical Discussion Paper on the general review of the High-Speed and Stability Standard under Performance Based Standards (PBS).
Brace yourself for some more acronyms! The three standards being reviewed in this consultation are: Static Rollover Threshold (SRT): Rearward Amplification (RA); and High-Speed Transient Off-Tracking (HSTO).
The Technical Discussion Paper has been released on the NHVR website and is available here. The paper is quite detailed and outlines each standard and any discussion points the regulator is already aware of regarding potential changes to that standard.
The NHVR is calling on industry for feedback by January 5, 2026. HVIA will provide a member-informed submission and is requesting preliminary feedback from members who wish to be involved by Monday, December 8, 2025. Due to the time of year, we will aim to make our submission well before Christmas unless any major concerns are raised.
This review is part of a series of evaluations being undertaking by the NHVR of all of the PBS Standards. An earlier review was conducted in 2023 focusing on the Low Speed Swept Path and Tail Swing Standards for PBS and can be found here.
Figure 1: A compliant L2 PBS truck-and-dog passing HSTO with an LTR of 1 (Source: NHVR website)
Vehicles entering the PBS scheme are assessed according to 16 minimum vehicle performance standards and four infrastructure protection standards. The SRT, RA and HSTO are three of the 16 safety standards which PBS assessors will follow and guide operators in combination designs which can meet these requirements.
The consultation reviews all three standards considered and challenges the testing conditions and ultimate requirements of the standards, encouraging stakeholders to offer any suggestions or ideas for improvements.
More general information on each standard and the current standard requirements can be found on the NHVR website here. The three standards being reviewed are:
> Static Rollover Threshold: The steady-state level of lateral acceleration that a vehicle can sustain during turning without rolling over.
> Rearward Amplification: Measures the ‘whip crack’ effect of a lane change manoeuvre.
> High-Speed Transient Off-Tracking: The lateral distance that the last axle on the rear trailer tracks outside the path of the steer axle in a suddent evasive manoeuvre.
Calls for feedback have been sent to both the PBS and Brakes and Related Technology Working Groups. If you have not received a communication and would like to join one or both of these working groups, please email r.michaud@hvia.asn.au to be added to the mailing list.