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Crash stats analysis sees maintenance and safety correlation

First report on combined NTI-NHVR data sees backing for random inspections


While it may seem self-evident that good truck maintenance is linked to better safety outcomes, insurer NTI and the National Heavy Vehicle Regulator (NHVR) have crunched the numbers to frank the assumption – with caveats.

Also involving the NTI-backed National Truck Accident Research Centre (NTARC), the report, Are good trucks the sign of a great operator? A special report into heavy vehicle roadworthiness, brings together for the first time de-identified data from NTI’s NTARC Major Accident Investigation Report (MAIR) and the NHVR’s National Roadworthiness Baseline Survey (NBRS).

At the basic level, the answer to the question in its title is it is likely that ‘good’ operators “are aware of the systems which pose the greatest safety risk and are ensuring that these systems are maintained appropriately”.

While report author and NTARC analyst Adam Gibson is careful not to overstate the case as a ‘causal relationship’ between shortfalls and accidents – a position repeated in the course of the analysis – the report finds a “correlation between operators with trucks inspected and found to be conformant to vehicle standards regulations and lower frequency and cost of truck crashes.

“Conversely, operators with trucks with minor defects showed a small (2 per cent) increase in the frequency of claims, while operators with trucks with major defects showed a significant increase (14 per cent) in the cost and frequency (7 per cent) of claims per powered unit per year.”

That said, non-conformity to standards for certain vehicle systems had the strongest correlation to increased truck-crash cost and frequency, specifically (in alphabetical order):

  • Couplings
  • Steering and suspension
  • Wheels and tyres.

Couplings showed a correlation with a 29 per cent increase in the frequency and a 22 per cent increase in the cost of claims.

For Wheel and Tyre defects the frequency was 32 per cent higher than the baseline while cost was 26 per cent higher.

There was also a lower but notable increase in claims for operators where one or more of their vehicles had defects associated with three other vehicle systems:

  • Lights
  • Steering and suspension
  • Structure.

One issue the analysis strikes involves braking, where the difference is very minor – at a 3 per cent higher frequency and 4 per cent higher cost when compared to the ‘all matched units’ baseline.

Read about the NHVR’s changes to roller brake testing, here

In looking to a reason, the report notes that NBRS braking figures were identified almost entirely by roller blade tester (RBT) equipment at the same time as the second edition of the National Heavy Vehicle Inspection Manual (NHVIM) came into play and the NHVR moved to standardise such testing.

The changes resulted in identification of a number of false positives, particular for trailing arm airbag suspension equipped trailers.

“As a result of the identification of these issues, a significant body of work was undertaken by the NHVR and a new National Roller Brake Testing Procedure was developed and has subsequently been implemented to address the identified issues,” the report notes.

The full report can be found here.


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