Major Accident Investigation Report


covering major accidents in 2017

Introduction

The 2019 edition of the NTARC Major Accident Investigation Report provides data insights from NTI’s heavy motor vehicle claims over $50,000 in 2017.

This report examines data from 756 claims, an increase of 150 incidents over the 2017 report.

This increase is driven by a mix of ongoing strong growth in NTI’s portfolio and by the effect of inflation resulting from the fixed $50,000 threshold for inclusion in the NTARC Major Crash Investigation Report.

Large Loss Frequency Over Time

Probability of a heavy motor vehicle having a large loss in a given year

What this shows is that around 0.24% of heavy motor vehicles will be involved in a large loss in any given year, or around 1 in every 400 trucks

Summary Of Findings

In 2017 most categories of incident cause remained generally consistent with previous reports, with some exceptions.

Incidents By Cause And Year

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* Editor’s note: Visible in the data is a sharp increase in driver error losses and a corresponding decrease in inappropriate speed, this arises from a change in categorisation for a subset of driver error claims.

Mechanical Failure - Steer tyre Failure

While mechanical failure is not one of the largest contributors to NTI’s large losses, it has consistently been the primarily causal factor in around 1 in every 20 large losses. There has been a 60% increase in mechanical failure large losses in 2017 (compared to an average of the 2013 and 2015 data) and as such deserves closer investigation.

Mechanical Failure Incidents
by Year

Proportion of large loss incidents with mechanical failure as primary cause

The steer tyre failure incidents in the data set all resulted in vehicles having high speed crashes with little to no opportunity for the driver to respond before striking barriers or leaving the roadway. Given the sudden and catastrophic nature of the crashes in these incidents, it is somewhat surprising that the only loss of life from these crashes in 2017 was that of a driver’s best friend, his faithful dog.

Steer tyre Failures By Speed Zone

Driver Error - Inadequate
Following Distance

Combining the Driver Error, Fatigue and Inappropriate speed cause codes allows the contribution of driver behaviour towards large losses to be tracked over time. The sharp drop in 2009 reflects a sharp reduction in fatigue losses between 2007 and 2009. This corresponds with the introduction of standardised heavy vehicle work diaries in most states in September 2008.

Proportion of claims with driver behaviour issue as primary cause

Driver Error Incidents By
Sub-cause

Examining the sub-causes within driver error reveals that nearly 1 in 3 driver error crashes results from inadequate following distance, which in the majority of cases then results in a ‘ran into rear’ crash.

Driver behaviour reflects the environment in which they operate, so any initiative would need to address following distance holistically across all vehicle categories.

Non-impact Fire

Non-impact fire was the major theme of the 2013 NTARC report and became a significant industry focus in the 12 months that followed. In 2015 there was a reduction of over 20% in the proportion of claims arising from fire and it has remained steady at this level in 2017. Notably while the overall proportion of non-impact fire losses has decreased, the distribution of the cause of the incidents has remained reasonably consistent, with only a small decrease in the proportion of fire originating in the cab/engine bay.

Wheel bearings, brake chambers, fuel lines, starter power cables; get any of these wrong and your ‘$200,000 prime mover’ might become ‘$3,000 of scrap metal’.

Proportion of Claims From Non-impact Fire

Examining the causes of these fires more closely starting with wheel end fires, we find that the predominant initial trigger for the fires are either wheel bearing or tyre failures. These are closely followed by wheel end fires initiated by the braking system. Brake fires typically result from some defect in the parking brake system which results in the spring-applied park brake to become lightly applied. Over time the dragging brake results in an accumulation of heat and this results in tyres, wheel bearing grease and other flammable material spontaneously combusting.

Fire Losses By Sub-cause

Fatigue

In 2017 there was a decline in the proportion of all large losses caused by fatigue, dropping by around 2 percentage points when compared to 2013/2015. At 9.8% of losses, this is the lowest proportion recorded since the inception of this report series.

Fatigue Incidents as Proportion of all Large Losses

Fatigue Incidents By State

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Relative Risk of Fatigue Incidents by State Corrected for Freight Volume - 2017

NSW and Queensland continued their trend of recent years with an increased proportion of fatigue losses. NSW is now just short of hosting two out of every five serious fatigue incidents.

In 2017, neither NT nor Tasmania had a large loss claim with nti resulting from fatigue, however given their small proportion of the freight task, just one or two fatigue incidents in a year would result in them being over-represented.

Fatigue Incidents by Time of Day

It has been a consistent trend throughout the history of the NTARC report that a disproportionate number of fatigue incidents happen between midnight and 6am and this continued in 2017 with over 40% of all fatigue losses occurring in this time period.

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Relative Fatigue Incident risk Corrected For Traffic Volume by Time of Day

As with the day of the week, by overlaying traffic volumes the relative risk of a fatigue incident at a given time of the day can be assessed.

00-0600 Hrs:

Measured in this way, the risk of a truck driving between midnight and 6am is over triple that of the daily average.

Roll Over While Tipping

Roll overs which occur while unloading tippers have consistently represented around 1 in every 20 large losses.

These 5% of losses are where there were no identifiable driver behaviour or other factors contributing to the incident and as such the event took place:

  • On substantially flat, firm and level ground
  • In the absence of excessively high wind
  • Without any driver error such as backing over already tipping material

Rolled While Tipping Losses by State

40% of these losses occur in Western Australia and the vast majority of these occur in a ring of between 50 and 350km radius around Perth.

These losses all involve multi-combination tippers carrying fertilisers/soil conditioners for agricultural use, predominantly lime sand. Lime sand is used to increase the pH of soil, particularly in wheat growing areas.

The combination of a dense, ‘sticky’ load, the length of tipping bodies on semi-trailer tippers and the lack of torsional coupling between units due to the 50mm pin type coupling on dollies results in somewhat of a perfect storm for tipping losses.

Multiple Vehicle Incidents

Proportion of Multi-vehicle Incidents

Over recent years there has been a steady increase in the proportion of large losses involving multiple vehicles. In 2015 this figure passed one in three crashes and in 2017 it rose further still to 37%.

All Incidents by at-fault party

Multi-vehicle Fatal Incidents by at-fault Party

Consistent with the 2015 data, when considering multi-vehicle incidents which do not involve a fatality, our insured was at fault 65% of the time.

For fatal multi-vehicle crashes in 2017, the other driver was at fault 83% of the time.

This is a decrease from the 93% figure seen in the 2015 data. NTI has been reporting on this particular statistic for a decade and the proportion has remained in a band between 80% and 100% throughout.

Proportion of Not-at-fault Fatal Multi-vehicle Crashes

This does not represent a final determination of whether a particular incident was a suicide - that determination has always been and remains the role of the coroner. However this analysis provides a significant insight into challenges which may exist in trying to address light vehicle at-fault multi-vehicle road deaths.

For the first time in the NTARC report, the contribution of suicide to this figure was evaluated.

37.5% of multi-vehicle fatal incidents in 2017 were either indicated or strongly-indicated to be suicide, with 20.8% being strongly indicated.