The NHVR has released an information sheet that clarifies that under the National Class 2 PBS Level 1 & 2a Truck and Dog Trailer Authorisation Notice 2022 (No.1) four axle trucks with tri-drive axle groups are not covered under the notice. The information sheet (link) provides examples of eligible PBS truck and dog combinations that can operate under the Notice and makes it very clear that the Notice does not provide access to rigid trucks fitted with tri-axle drives.

From the definitions in the notice you can see where the confusion comes from:
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   Definitions

    (1)         Unless otherwise stated, words and expressions used in this Notice have the same meanings as those defined in the     HVNL.

    (2)          In this Notice PBS truck and dog means a 3 or 4 axle rigid truck towing a 3, 4 or 5 axle dog trailer that is the subject of a

    (a)          passes the PBS Bridge Loading standard as Tier 1; and

    (b)          for PBS Level 1, has a maximum overall length no greater than 20.0m; and

    (c)          for PBS Level 1, has a maximum overall height no greater than 4.3m; and

    (d)          for PBS Level 1, has a maximum operating mass no greater than 50.5t; and

    (e)          for PBS Level 2, has a maximum overall length no greater than 26.0m.

The notice makes no mention of twin steer or tri-drive groups which is different to the National Class 3 Truck and Dog Trailer Mass Exemption Notice 2020 (No.1)  

    6.       Application

    1)      This notice applies to a Truck and Dog heavy vehicle where:

    a)      the combination does not exceed 19m in length; and

    b)      the truck has a single steer axle or a twin steer axle group at the front, and a dual-drive tandem axle group at the rear; and

    c)       the dog trailer has either a single axle or a tandem axle group at the front, and a tandem axle group at the rear.

A review of the NHVR PBS Configurations chart (link) only shows tri-drive groups in road trains.

We suggest that you check your Vehicle Approvals and Access permits to make sure that you are operating under the correct scheme.

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