Jun 152011
Dear IFRTT Forum subscriber

It appears to have become traditional for these newsletters to comment on the weather.  Here in the southern hemisphere we are just beginning our winter so most readers will be entering their summer.  In Auckland we have just had the warmest May on record with average temperatures over 2°C above normal.  It is still relatively warm with daytime highs around 17-18°C.  Not good for the ski field operators or the skiers but the rest of us aren’t too unhappy.

Last year I told you about a Rule change here that provided for vehicles that are larger and heavier than allowed by the dimensions and mass limits to be allowed to operate under permit on routes that could accommodate them.  In implementing this Rule change the government’s regulatory agency has used a hybrid performance-based standards approach.  Over-dimension vehicles at standard weights have been permitted general access to the network provided that their road space requirements during low speed turning manoeuvres are no greater than those of the worst-case standard vehicles.  Design envelopes that achieve this performance have been developed for the most common vehicle configurations and vehicles that fit these envelopes do not need to be individually assessed.  Other designs are possible but these are required to be individually assessed.  These same vehicles can be permitted to operate at higher weights on specific routes that have been assessed as suitable.  Vehicle configurations that do not achieve the low speed turning performance required for general access can still be permitted but on a route-specific basis.  Quite a large number of these vehicles are now operating at standard weights but he numbers operating at higher weights are still relatively small.  The photos below show a log truck that has recently been approved.  With rear overhang this vehicle is 23.3m long compared to the standard legal limit of 20m.  As shown in the first two photos it is loaded to 44 tonnes which is the standard legal weight limit while in the third photo it is loaded to 51 tonnes.  On approved routes it could potentially achieve up to 57 tonnes.  The additional length allows the logs on the trailer to be carried as two packets giving a very low load height and hence very good rollover stability.

I wish you all a pleasant summer or winter.



John de Pont

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