Three new proforma designs for high productivity vehicles – a nine-axle logging truck and trailer unit and nine-axle and 10-axle B-train combinations – have been approved by the New Zealand Transport Agency.
The trio are the first proforma designs that meet new performance based standards (PBS), which were released last month by the Agency.
Prototypes of the two B-train designs passed low-speed and onroad validation testing by TERNZ in May.
As part of the process of developing the new PBS, the Truck Trailer Manufacturers Federation (TTMF) commissioned (with NZTA approval) the development of the two new proforma B-train designs to comply with the new PBS. 
The nine-axle B1233 combination – a 23m unit, comprising a 6x4 tractor unit and a six-axle Roadmaster B-train – has been run by Vowles Transport since last December. 
The 23m 10-axle B1243 combination – a 6x4 tractor and a B-train with four axles on the front trailer (the rearmost axle a steerer) – was built by Fruehauf for K&S Freighters, and went on the road in March. 
It's capable of carrying two 22.5-tonne, 20-foot containers....or one 40ft container and one 20-footer. And the design is equally applicable to flatdecks or curtainsiders.
Combinations built to the proposed logtruck PBS – comprising an 8x4 truck and five-axle trailer – have been permitted to run in the central North Island on specific route permits over a longer period…at overall lengths of up to 23.5m, that including an allowable rear load overhang of up to 1m. 
This enables them to transport 6.1m logs (an industry standard length) as a two-packet load on the trailer, while also providing "substantially improved rollover stability for negligible additional risk due the additional length," says TERNZ.
The PBS are used to assess whether non-standard heavy vehicle designs will meet safety performance requirements, equivalent to standard vehicles – as specified in the Vehicle Dimensions and Mass Rule 2016 (VDAM). 
As NZTA points out, alternative heavy vehicle combinations such as HPMVs "have to be carefully designed to make sure they meet the principle set by the VDAM Rule – that they are as safe as a standard vehicle." 
Hence the need for PBS to help determine the safety of new HPMV designs – primarily "how the vehicle fits on the road and its ability to take avoidance manoeuvres at speed without losing control."
The Agency says that until now, NZ's PBS were largely based on standards developed overseas: "The new PBS are better suited to NZ's more frequently narrow and winding roads."
NZTA regulatory general manager Kane Patena says the new PBS encourage better design and safer performance on the network: "In particular, they'll exhibit improved tracking within a lane, on tight curves – and allow productivity improvements such as being able to simultaneously cart a 20-foot and 40-foot ISO container. 
"The new PBS will enhance safety while maintaining – or even improving – productivity."
They also "provide a transparent and consistent process for assessing non-standard heavy vehicles. They'll provide certainty to the industry on what truck configurations they can put on the road, particularly for the new HPMV fleet."
The new PBS were developed in consultation with industry representatives, were peer reviewed internationally, confirmed by computer modelling and then validated by practical onroad trials, carried out by TERNZ. 
The new PBS are available at https://www.nzta.govt.nz/commercial-driving/high-productivity/performance-based-standards. 
NZTA says other proforma designs, which are developed "based on greatest identified need," will be released. A framework for assessing unique designs will also be released.