Last week, the National Heavy Vehicle Regulator (NHVR) released the final Consultation Paper for the revised Directional Stability Under Braking (DSUB) Technical Standard and implementation approach to industry.
This paper is out for consultation from Thursday, November 20, 2025 until Monday, December 15, 2025.
DSUB updates were initially signed off by ministers in November 2019 following the PBS Review Project led by Dr John de Pont from TERNZ Transport Research Ltd.
Now, five years on, we are set to see the standards released early in 2026 and tentatively in force from July 1, 2026 pending the final release from NHVR.
One key change is that new VINs entering the Performance Based Standards (PBS) scheme for the first time will no longer be able to comply with the DSUB standard by fitting Load Proportioning Valves.
Trailer Electronic Braking Systems (EBS) will become the new norm for PBS trailers, including dollies. Heavy combinations will require electronic braking control lines all the way through, and voltage must be sufficient to power all trailer EBS units connected.
It is a welcome relief to see the upgrade of the PBS fleet come into effect, and the latest EBS’s mandated where possible. Key changes between the most recent consultation which was released mid-year and the latest one are:
> Updates to grandfathering provisions which will now utilise a more traditional implementation, whereby first-time VINS to PBS must meet the new DSUB standard. This is a walk back from the initial proposal to retrofit heavy vehicles or trailers every time a new vehicle approval is required due to the addition of a new VIN to a vehicle combination. We welcome this change as it is a practical and simplified approach and still allows for an improved PBS fleet condition and enhanced safety over time.
> To align with the modified grandfathering approach, an extra requirement will be placed on the towing vehicle to be capable of powering trailer EBS modules – a provision which older vehicles may not have had from factory as it was optional for many years and only mandated in the last decade. This is a departure from Vehicle Standards Guide (VSG) 25 which indicates that trailer EBS units must only be powered if the towing vehicle is capable of doing so.
> There is also now an electric control line exemption for dolly trailers used in multi-combinations with greater than five trailers connected. These dollies must still be fitted with TEBS and powered; however, the Controller Area Network (CAN) communication for an electronic brake signal will not be a requirement for the dollies where there are greater than five trailers in combination. This does not prohibit some operators from having the communication, but was to acknowledge that the ISO11992-2 Application Layer does not list addresses for more than five trailers in series. Some systems have assumed the next logical sequence of addresses to achieve longer combinations. HVIA will work with members in the future to challenge the limitations of the ISO11992-2 application and explore the viability of adding addresses for more trailers to capture the real-life use cases in the Australian market.
The final Consultation Paper has been circulated to members who are in the Brakes and Related Technology and PBS Working Groups. If any members have not seen the paper and would like to, please email r.michaud@hvia.asn.au.
HVIA will finalise a collective response to the Consultation Paper and make this available on the HVIA website in the coming week. Thank you to those who have already contributed and have been part of the consultation process. The previous submission made by HVIA earlier this year regarding DSUB can be found here.