PBS Combinations & Vehicle Configurations
One of the most important considerations for any freight task is the vehicle or vehicle combination that is to be used to complete that task. There is often a conflict between what is optimum for the freight and what is permitted within the Australian Design Rules (ADRs), the National Heavy Vehicle Law (NHVL) or road access requirements. An example of this is a semitrailer carrying lighter palletised freight which can't load to maximum weights as it is limited to 22 Pallets due to the ADR dimension limits for trailers. PBS combinations can be put together outside of these statutory limits that can be specfically tailored to the freight task unlocking additional productivity for operators. This has seen the Performance Based Standards (PBS) approval of semitrailers up to 30 Pallets in size.
What are the different PBS combinations?
There is a multitude of different combinations operating under the PBS scheme currently on the road ranging from standard to revolutionary in their design. The variety in the freight task and the roads combinations are used on means there is not a one size fits all solution. A brief description of the common PBS combinations is included below and well as information on why PBS might be desirable and/or required. Typically this is for the following reasons;
Increased combination mass limits
Increased dimensional allowances
Potential to access more locations than prescriptive vehicles of the same type can access
Combination falls outside of Vehicle Standard Requirements ie. Split axle groups
Click the relevant page link for further information on any of the below combinations.
PBS Truck & Dog
Detailed information including masses and lengths - PBS Truck & Dog
Truck and combinations do not necessarily require PBS to be able to access the road network, however additional mass and dimension allowances can make running your truck and dog under PBS an attractive proposition. Typically 3A Dogs are run under PBS purely for the additional mass, 4A Dogs are run under PBS for additional mass and the ability for the overall length to be in excess of 20m. 5A and 6A Dogs are not general access vehicles and typically require PBS to operate apart from niche examples were they may be able to operate on B Double and Road Train routes under notice or permit in some jurisdictions.
PBS A Doubles
Detailed information including masses and lengths - PBS A Doubles
An A Double combination refers to a category of combination that consists of a Prime Mover towing two trailers which is where the "double" part of the name comes from. The "A" in the title refers to the drawbar coupling between the two trailers. In a non PBS context they are often called road trains or more specifically, Type 1 Road Trains. A Doubles can provide several benefits over a conventional B Double, including better turning performance, higher combination weights and larger cubic capacity.
PBS A Triples
An A Triple is built upon an A Double but with an additional dog trailer or dolly and semitrailer towed behind the second trailer. In a non PBS context, they are often called road trains or more specifically, Type 2 Road Trains. Total combination weight can be up to 141.5t when operating at HML with overall lengths up to 53.5m. As such access to is limited to PBS level 4 networks which are typically limited to regional areas with less traffic. (Image credit - Trailer Magazine)
PBS AB Triples
An AB Triple consists of three trailers joined via one A type coupling (drawbar and dolly) and one B type coupling (turntable on the rear of a trailer). Overall lengths are typically up to 36.5m, which is the same as A doubles and B Triples meaning there cubic capacity is similar. The advantage of an AB Triple is the additional axle group which increases the maximum weights up to 113.5t. This makes them ideal to function for heavier freight tasks such as bulk transport of aggregate, grain, fertilizer and other commodities.
PBS B Triples
A B Triple adds an additional lead trailer to the common prescriptive B double. This extends the length up to 36.5m with the typical carrying capacity being 42-46 pallets. whilst they are suitable for a range of freight tasks, most commonly they are used by general freight curtainsider and refrigerated transport companies doing linehaul work. It is often possible to repurpose existing B Double sets to form B Triple sets, massively increasing productivity with existing assets. Pocket B triples using tandem axle trailers from 19m B Double sets are also possible, creating a 26m combination with weights of up to 74.5t.
Quad or Split Axle Semis
Semi trailers have been a mainstay for the the transport industry. The most common configuration in Australia is the three-axle (tri-axle) semi which can carry up to 22.5t on the axle group. In applications where additional mass is required, particularly with containerised freight, a PBS Quad Axle semi-trailer introduces a 4th axle which is steerable to the group. This allows the axle mass to be up to 27.0t, resulting in an overall combination mass of up to 50.5t when used with a 6x4 Prime Mover. An alternative option rather than running a 4th axle is splitting the tri-axle group into a standard tandem and a single steerable axle which allows mass of up to 17.0t on the tandem and 9.0t on the single for 26.0t across the axles. These additional weights can also be used to increase the pallet carrying capacity through larger and longer semitrailers.
How can BTT help you choose the right combination and get the most out it?
At BTT Engineering we have helped hundreds of satisfied clients to achieve great results with a multitude of different PBS combinations. Through collaboration with you as the operator and BTT as the PBS and Access experts we can come to the best solution for your business. The information you can supply to us is knowledge of your existing assets and expertise on how the freight is best transported. For example: do I have rigid trucks or Prime Movers? Mainly lead or rear trailers? Do I have dollies I want to use? Do I need to be able to unload without uncoupling? Would I prefer 1 larger trailer rather than a B Double? Knowing this, BTT can bring their experience of the types of combinations which would work in your application and importantly get access to the roads at the weights that are required. This will ensure you have a PBS combination that is practical, useful and productive for your business.
PBS combinations FAQs
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'PBS Rated' or 'PBS Approved' are terms that you might hear getting thrown about but what do they mean? These actually are not formally defined terms and often cause more confusion. You might be more familiar with a B Double rated truck that can be hooked up to any B Double rated trailer and form a compliant combination provided it is within the required dimensions. Within the PBS scheme, only approved combinations can be used, therefore you can't mix and match vehicle units unless each possible combination has been assessed.
Using a 'PBS Approved' or 'PBS certified' unit for a new certification can still be advantageous however as the previous certification data can be used rather than the unit being measured and inspected. This can save you time and money.
Unlike B Doubles and Road Trains, units used within a PBS combination are not required to be "PBS rated". It should be noted through that if your PBS combination is classified as a B Double or Road Train that all units must have the relevant rating for this combination type. Despite there not being a PBS rating, there are several essential items that trucks and trailers should have to ensure they can be used as a PBS combination and gain access to the relevant road network.
Truck to have appropriate Gross Combined Mass
Truck to be fitted with ABS or EBS
Truck to be eligible for 6.5t steer axle (Refer to National Heavy Vehicle Regulator website)
Trailer ATM high enough for the intended weights
Trailer fitted with LPV at a minimum or ABS/EBS for combinations longer than 26m (LPV on dollies or longer combinations is fine)
Truck to be fitted with the latest safety equipment such as but not limited to lane keeping (not PBS related but is a common access requirement when longer than 26m on the Hume Hwy or in and around Sydney)
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The intent of the PBS scheme is that there is an infinite amount of different combinations with different performance specifications that could each affect what roads they are suitable for operating on. This is very difficult to manage from a road manager's perspective. To streamline things, there are four Performance Based Standards levels, which were originally setup to reflect different types of existing prescriptive vehicles on the road. This allows road managers to give road access 'in bulk' provided the performance standards are met, the same way a B Double can get access to the B Double network provided it meets the prescriptive standards. Below are the 4 PBS Levels along with the prescriptive vehicles they were based on.
PBS Level 1 - General Access Vehicles
PBS Level 2 - B Doubles up to 26m
PBS Level 3 - Type 1 Road Trains
PBS Level 4 - Type 2 Road Trains