One in six heavy vehicles checked during a multi-agency operation near the WA-SA border last week was found to have defects.
The figures come after a three-day blitz in Eucla that resulted in police from Kalgoorlie, Norseman, Esperance, Eucla and Perth targeting road safety issues and stopping the flow of illicit drugs into Aboriginal communities as part of operations Austrans and Pure.
Commander Alf Fordham said the number of heavy vehicles issued with work orders was not only significant, but also unnerving.
Police stopped 564 trucks and issued 86 defect notices.
"By way of example about the roadworthiness of vehicles, there was one truck that was so heavy it actually damaged and dented the road," Cdr Fordham said.
"The driver was 30 per cent over his weight limit - he was carrying an excavator."
The offence was one of 35 cautions, warnings and infringements for permit breaches.
Defects ranged from brakes, frayed seatbelts, to bald tyres, to vehicles dropping a lot of oil on the road.
One truck that was stopped was found to have its load of chemicals spilt throughout the truck, with both drivers lacking appropriate training or equipment to deal with potential chemical hazards.
More than a dozen truck drivers were cautioned or fined for seatbelt offences, including a driver and his passenger who were caught not wearing seatbelts.
Five drivers were cautioned or fined for being unlicensed, suspended or disqualified from driving.
Officers discovered one driver, who was driving from NSW to WA, was on a student visa.
Supt Darren Seivwright said the results of the operations demonstrated the need for operations such as Austrans.
"The number of defects detected is a concern as they can result in serious injury or death, and even significant damage to infrastructure, including roads that costs taxpayers considerable sums of money to repair," he said.
Under Operation Pure, 743 light vehicles were stopped and 81 infringements and 161 cautions issued.
Offences including possessing a prohibited drug, possessing drug paraphernalia, possessing a prohibited item (pepper spray) and possessing explosives (fireworks).