Hi John, hi all,
Here in Northern Europe the weather situation is the opposite of yours, colder than normally this time of the year. We have been waiting for the spring to arrive three-four weeks longer than usually, in Stockholm we still have 5-8 degrees below zero during nights. We would love to get some of the heat you have in NZ.
Interesting case you describe, the dilemma cannot be unique to NZ. At least not when it comes to load distribution and thereby CoG height. Perhaps a little more rare when combining with your operating conditions.
A few year ago I had the opportunity to ride with some milk tank trucks on your beautiful Northern island. A very dynamic ride I would say, in terms of road curvature, speed, topography, braking/acceleration etc. These tank trucks had rather low CoG, low cabs with low chassis position and elliptic tank cross-sections, thereby managing the dynamic load transfer very well (although still quite tough for the truck durability). Now perhaps the container trucks does not operate the roads of the milk trucks, but probably they ride with more dynamics than most container transports e.g. in Europe with the more straight roads.
My point is that a solution should be sought not only in the basic vehicle mechanics (i.e. SRT), but also in the truck operation. And what kind of braking system were the rolled over trucks equipped with, did any of them have ESP?
Best regards Erik
Erik Dahlberg, PhD
Senior Manager | Vehicle Regulations | Scania CV AB
Phone: +46 8 553 823 11 Mobile: +46 7 061 823 11
SE 151 87 Södertälje, Sweden
www.scania.com | www.facebook.com/scaniagroup
-----Original Message-----
From: Technical, operational and economic aspects of road freight transportation [mailto:[log in to unmask]] On Behalf Of John de Pont
Sent: den 4 april 2013 23:12
To: [log in to unmask]
Subject: IFRTT Newsletter March 2013
IFRTT Newsletter March 2013
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
***********************************************************
The ROAD-TRANSPORT-TECHNOLOGY mailing list is published by
International Forum for Road Transport Technology
www.road-transport-technology.org
***********************************************************
***********************************************************
The ROAD-TRANSPORT-TECHNOLOGY mailing list is published by
International Forum for Road Transport Technology
www.road-transport-technology.org
***********************************************************
|