Finding into death of Michael John Jonson
Deceased
Michael John Jonson
Demographics
48y, male
Date of death
2007-04-09
Finding date
2015-07-27
Cause of death
Multiple injuries sustained in a motor vehicle incident (driver)
AI-generated summary
Michael Jonson, age 48, died from multiple injuries sustained in a motor vehicle collision on the Melba Highway near Vasey Houghton Bridge when a trailer being towed by another vehicle detached and crossed into his path. The trailer had been manufactured with design defects including inadequately welded drawbar joints, undersized leaf springs, and poor suspension mounting, rated above its structural capacity. Modifications by subsequent owners further compromised its integrity. On the day of the incident, the trailer had lost a rear wheel and was being towed on three wheels with an overload of approximately 1450kg ATM. The drawbar failed due to fatigue crack propagation accelerated by the three-wheel configuration and excessive loading, causing the trailer to detach. The primary causative factor was substandard manufacturing unable to withstand subsequent modifications. Registration of the trailer in Victoria might have identified defects through visual inspection and referral to a VASS engineer, though design defects may not have been apparent.
AI-generated summary and tagging — may contain inaccuracies; refer to original finding for legal purposes.
Error types
Contributing factors
- Trailer manufactured with design defects in drawbar welding and joint configuration
- Drawbar connected with incomplete welds in high-stress regions prone to fatigue failure
- Leaf springs undersized relative to registered Gross Trailer Mass (2000kg)
- Suspension suspension travel reduced by 40% through lowering modifications exceeding VicRoads guidelines
- Trailer loaded to approximately 1500kg (exceeding safe ATM of approximately 1100kg after modifications)
- Trailer towed on three wheels due to rear off-side tyre failure
- Trailer not registered in Victoria; substandard manufacturing not identified through registration inspection
- Fatigue crack pre-existing in drawbar, accelerated by three-wheel towing and overloading
- Smooth bitumen surface and slight dip on Vasey Houghton Bridge precipitated drawbar failure
Full text
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