The National Heavy Vehicle Regulator has launched a fresh review of key PBS safety standards, asking industry to help shape how high productivity vehicles are tested and approved.
Alongside its final consultation on the Directional Stability Under Braking (DSUB) standard, the NHVR has released a new Technical Discussion Paper on three high-speed and stability measures under the Performance Based Standards scheme.
These are: Static Rollover Threshold (SRT), Rearward Amplification (RA), and High Speed Transient Off-Tracking (HSTO).
What is actually being reviewed?
The three PBS safety standards help define how a combination behaves when things go wrong on the road.
They are among the 16 minimum performance standards PBS vehicles must meet, along with four infrastructure protection standards.
The NHVR paper questions whether the current test conditions and pass levels are still fit for purpose.
It invites operators, manufacturers, engineers and assessors to suggest improvements or flag any unintended consequences of the existing rules.
Why SRT, RA and HSTO matter for operators
Static Rollover Threshold looks at how much sideways force a vehicle can handle in a turn before it rolls.
Higher SRT values indicate greater resistance to rollover in curves and during emergency manoeuvres.
Rearward Amplification measures the “whip crack” effect when a combination changes lanes quickly.
It checks that the trailers do not swing harder than the prime mover and destabilise the whole set.
High Speed Transient Off-Tracking measures how far the last axle on the rear trailer tracks outside the steer axle path in a sudden evasive manoeuvre.
This is critical for staying within lane lines and avoiding roadside hazards during high-speed events.
For PBS vehicles, these standards guide how designs are assessed and influence which combinations can be put to work.
Changes to the PBS safety standards could alter how certain combinations are configured, tested and approved.
How and when to provide feedback
The NHVR is inviting submissions on the discussion paper until 5 January 2026.
The paper explains each standard in detail and highlights issues that have already been raised with the regulator.
HVIA will lodge a member-informed submission and is asking members to provide preliminary feedback by 8 December 2025, so any major concerns can be addressed before Christmas.
The review forms part of a broader overhaul of PBS metrics.
An earlier phase in 2023 examined the Low Speed Swept Path and Tail Swing standards, with outcomes now published on the NHVR website.
Anyone working with PBS vehicles, braking systems, trailer design or fleet safety is encouraged to engage with the process and help refine the next generation of PBS safety standards.