The most telling signal for how often a heavy transport vehicle operator is likely to claim, and how costly claims will be, is the condition of the fleet’s tyres, an ambitious study examining ten key truck maintenance requirements concludes.

Trucks with poor maintenance in two categories – wheels & tyres and couplings – experience significantly more expensive claims, and also claim more frequently, the research by NTI found.

The study also examined brakes, steering and suspension, structure, seats, lights, mirrors, windscreens, engine and driveline to determine the correlation between poor maintenance and claims.

“The findings … suggest that simply checking the condition of the tyres on a truck may provide a significant insight into effectiveness of transport safety management practices within the business operating that vehicle,” the report from NTI says.

The report says the findings “only demonstrate there is a correlation”. Very few serious crashes are linked to mechanical failures and the results may reflect that maintenance practices indicate the fleet operator’s broader approach.

“It would appear likely … that operators with effective maintenance regimes may also have better general systems to manage risk within their business and therefore better outcomes for the factors known to directly cause incidents such as fatigue and driver behaviour,” the report says.

There are “significant opportunities for future research to determine the causative mechanisms behind the correlations found within this report,” NTI says.

NTI found a particularly clear correlative link in two categories. Transport companies with poorly maintained wheels and tyres showed a 32% increase in frequency and a 26% increase in the cost of claims. Couplings that were neglected were connected with a 29% increase in frequency and a 22% increase in the cost of claims.

“This does not show crashes were caused by defects in those systems but that operators with trucks in which couplings, wheels and tyres were not well maintained, were involved in a greater number of claims,” NTI’s Transport & Logistics Risk Engineer Adam Gibson, who authored the report said.

The study supports the use of random on-road heavy vehicle inspections as part of an effective assurance regime, NTI says, although not “to directly manage risk by ensuring vehicle standards are complied with”.

“Rather, it indicates which operators may pose a higher risk via whatever undetermined mechanisms link the vehicle standards non-conformity and increased cost and frequency of crashes.”

The findings are the result of a complex study made possible as, for the first time, data on the condition of heavy vehicles from the National Heavy Vehicle Regulator and on heavy vehicle crashes from NTI, Australia’s largest truck insurer, were combined.

Traditionally there has been very little hard evidence proving a link between vehicle maintenance and major incidents because of a separation between the organisations that hold data on vehicle condition and organisations that have access to data on crashes.

The study set out to definitively answer whether “transport operators with trucks that are well maintained have better safety outcomes”.

“At its heart, this report sets out to answer a very basic question,” it says.

Operators conforming to vehicle standards regulations had fewer and less costly truck crashes. Operators with trucks with minor defects showed a 2% increase in the frequency of claims, while operators with trucks with major defects showed a 14% increase in the cost and a 7% increase in the frequency of claims per powered unit per year.

Operators that had vehicles with defects in their braking system showed only 3% higher frequency and 4% higher claims costs.

That was attributed to a significant overhaul of the system for testing braking systems since 2016, when the NHVR coordinated the National Roadworthiness Baseline Survey (NRBS), creating a snapshot of the mechanical condition of Australia’s heavy vehicle fleet. The NTI study combined that snapshot with its own extensive data on Australian heavy vehicle road crashes.

NTI processes more than 20,000 heavy motor insurance claims each year and says this “creates a rich repository of data on one form of harm – property damage – arising from the operation of heavy vehicles”.

The sample of vehicles from the NRBS comprised 7130 powered units and 3936 trailers for a total of 11,066 units. There were 2710 vehicles subject to NRBS inspections which matched with vehicles in the NTI portfolio. These vehicles were associated with 668 different policies.

In a remarkable endeavour, the NTI study overcame significant logistical challenges to preserve privacy.

“It was necessary for this research to be undertaken on data which contains personal identifiers, but to do so in a way which never allows a party to see the other’s data directly,” NTI said.