17 August 2017

A logging trailer tipped as the truck and trailer made a right angle turn at a main highway junction.

Circumstances

A truck and trailer unit loaded with pulp logs was turning at right angles around a traffic island from one state highway onto another. The intersection was clear of traffic and the driver was able to make the turn at what appeared to be a safe speed. However, the trailer started to tip part way around the island and eventually tipped and spilled its load onto the grass verge.

Investigation

An examination showed tyre marks from almost the start of the turn and then gouge marks at about the apex of the turn suggesting that a front left tyre of the trailer was either flat or partially deflated, causing the tyre marks and the gouging of the road surface, and contributing to the accident.

Another contributing factor is thought to be the incorrect loading of the trailer which had longer, heavier logs on the top of the load causing a top-heavy load situation.

The corner is also known for the camber which falls away from the road centre to the outside causing balance of the load and vehicle to be thrown to the outside of the turn.

In summary, the accident was caused by a combination of the following:

• trailer tyre deflation
• incorrect loading
• poor road shape

WorkSafe New Zealand advice

1. Check and ensure that all tyres are correctly inflated and meet road transport standards.
2. When loading pulpwood, balance loads properly if possible, by loading longer larger logs on the bottom of the load.
3. Be aware of incorrect, unusual or poor road shaping on your regular cartage routes and watch carefully for them if on a new route.

To which industries/sectors or matters will this information be relevant?

• Forestry
• Mobile plant
  
  

Published: May 2010. Updated August 2017.