Performance Based Standards (PBS) has proven to have had much success in improving both safety and productivity. According to NHVR statistics, PBS Vehicles make up nearly 30% of new trailer builds in Australia and NTI insurance data shows that PBS vehicles are on average 60% less likely to be involved in an accident on a per km basis, refer Review of Major Crash Rates for Australian Higher Productivity Vehicles: 2015-2019.
However, recent data also shows that PBS is very much the Truck and Dog and A-Double scheme, particularly in the Eastern NHVR states. The National PBS Truck and Dog notice allows Level 1 and Level 2 Truck and Quad Dogs up to 20 m and 26 m access to PBS networks without need for a permit. However, similarly configured B-doubles with equivalent axle groups and weights are not given the same privileges. Instead, they are required to get a permit to travel on the network.
VicRoads have provided numerous pre-approved bridge networks for A-Doubles up to 30 m and 36.5 m with a variety of different axle spacings. However, B-Triples with complying bridge axle spacings, must go through a more costly and time-consuming bridge assessment process, despite being a more dynamically stable combination. A B-triple is disadvantaged not because it does not comply with the bridge axle spacings or PBS, but because it has a B-coupling (roll-coupled, i.e., fifth wheel) rather than an A-coupling (non-roll coupled, i.e., pin or ball coupling). Even longstanding transport industry veterans get lost on this distinction.
Historically, A or B couplings were considered an important safety distinction. Consequently, prescriptive B-doubles were provided more weight than Truck and Dogs and more access than road trains. However, as recent research published by NTI shows, it may be less important than previously thought. In any case, whether a vehicle is roll-coupled or not has no bearing on pavement or bridge impacts.
Nevertheless, the outdated notions of classifying trucks by what they look like rather than how they perform has been carried through to the current PBS Scheme. PBS relies on a complex foundation of laws and unfortunately, we still have not managed to break the shackles of out-dated vehicle definitions.
Whilst it is important to put boundaries on what is possible with prescriptive vehicles. These definitions stifle innovation and distort the PBS market.
There are many vehicle definition issues which need revision. For example, ADR 43/04 requires that a motor vehicle be comprised of two axle groups, the first which must be either a single-steer or twin-steer axle group. This precludes the use of more innovative vehicle configurations like tri-steers. It also makes it harder to overcome historical perceptions of how damaging steer axles are rather than how damaging each type of axle group and tyre configuring is. Similarly, the various ADR definitions of semi-trailers and dollies are outdated and need revision.
However, perhaps an easier and more fruitful start would be overcoming the terminology embedded in the current PBS Truck and Dog notice. Rather than a Level 1 and Level 2 PBS Truck and Dog notice, we should replace the words Truck and Dog with Vehicle combination.
The notice could then refer to approved axle patterns and remain silent on vehicle configuration which has no bearing on pavement or bridge impacts.
1-2-2-2 could therefore be a 3-axle truck and 4-axle dog OR 3-axle prime mover and tandem axle B-double trailer OR 3-axle prime mover and tandem-tandem semi-trailer. The remaining PBS vehicle standards are now mature enough to tolerate the removal of this arbitrary distinction. Similarly, 1-2-3-3-3 could be a B-Triple or A-Double with Tri-axle Dolly.
PBS was supposed to move away from using prescriptive terms like B-double and road train and be agnostic when it comes to vehicle configuration.
It is time that B-doubles. B-triples and other innovative combinations get the same access and privileges as truck and dogs and A-doubles under PBS and not be disadvantaged because of outdated notions what a vehicle should looks like.
We can then evolve PBS form being the truck and dog and A-double scheme to being the innovative High Productivity Vehicle Scheme.