Inappropriate speed for prevailing conditions remains the major cause of significant truck crashes, according to a biennial study.

Such accidents, which include travelling too fast on roundabouts, when cornering or changing lanes, represented 21.4% of losses during 2015, down from 27% in the previous study by National Transport Insurance’s (NTI) National Truck Accident Research Centre.

The study reviewed 606 truck crashes with losses above $50,000 reported to NTI during 2015. The incidents accounted for $85.4 million in settlements and about 75% of claims by number.

Fatigue accounted for 12.2% of losses, static from two years earlier, with more than 80% of the losses occurring in the eastern states.

About 9% of losses were due to fires triggered by electrical failure and other issues, while only 3.5% were attributed to vehicle maintenance.

Some 56% of major crashes happened between 8am and 5pm, when roads are busiest, while single-vehicle accidents accounted for 66% of losses.

The driver of a car or light vehicle was found to be responsible in 93% of multi-vehicle fatal incidents, with general behaviour and attitudes, including use of mobile phones, of growing concern.

“These are fundamental social issues that now need to be addressed or the road safety gains introduced in the past generation will be lost,” the report says.

The Bruce section of the National Highway in Queensland continued to be the worst performer, given its relatively minimal share of freight movements.

“We are reminded that there is no room for complacency as the reliance on freight movements by road remains pivotal to Australia’s economic stability and growth,” the report says.