Apr 052013

Greetings from the deep south,

It has become mandatory to begin these newsletters with a weather report.  Here we have had one of the driest summers on record.  The whole of the North Island is officially in a state of drought which is causing significant issues for our farmers.  The Minister of Finance has claimed that the cost to the economy could exceed $2b.  However, for the rest of us it feels like it has been a great summer.

We have recently had an issue arise here with the stability of trucks carrying high-cube ISO containers loaded to near maximum weights.  As many you may be aware New Zealand has a requirement that large heavy vehicle must achieve a minimum level of rollover stability.  The static rollover threshold (SRT) must exceed 0.35g.  Most of these container trucks have been certified as meeting the rollover stability requirement on the basis that the payload carried by the container is mixed freight and thus that the centre of gravity of the payload is located at 40% of the container height.  In last few months several of these vehicles have rolled over and it was found that the containers were loaded to the roof with uniform density product.  Thus the centre of gravity of the payload was actually at 50% of the container height.  The problem is compounded because often the container is already packed and sealed when the truck collects it and the driver does not know how the load is distributed inside the container.  Similarly enforcement officers cannot easily see the load distribution.

Faced with the dilemma the government transport safety agency has taken the position that as the container could be loaded to the roof with uniform density product, this is the potential worst case load and the certification for rollover stability should be done on this basis.  The issue that then arises is that most of the existing vehicles undertaking this transport are tridem skeletal semitrailers which have great difficulty in achieving the required level of rollover stability with higher container weights.  At the time of writing the way forward has not been fully resolved.

This issue of the poor rollover stability of vehicles transporting heavily loaded high-cube containers cannot be unique to New Zealand although in other jurisdictions there is no minimum rollover stability requirement and thus it is legal to operate vehicles with poor rollover stability.  If anyone has any information on the rollover rates of these vehicles or on any counter-measures to improve their performance I would be interested to hear from them.

Drive safely.

John de Pont

Vice President, Asia-Pacific

 Posted by at 5:09 am

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