When transport trucks hauling garbage along Ontario's highways are inspected, nearly one in three is pulled off the road, CBC News has learned.

The trucks can be deemed unsafe due to faulty brakes, damaged wheel assemblies and a host of other problems that can create dangerous situations along routes like Highway 401, Canada's busiest stretch of road.

Last year 360 of the 1,182 transport trucks hauling garbage that were inspected — or 30.5 per cent — were put out of service, according to numbers obtained from the Ministry of Transportation.

The average for transport trucks in general was 22.7 per cent.

'Thirty per cent is a very high safety rate in terms of infractions,' says OPP Sgt. Dave Rektor. (The Associated Press)

Even more garbage haulers failed their inspections in 2013 and 2014. In those years, 32 per cent were deemed unsafe.

"Thirty per cent is a very high safety rate in terms of infractions," says OPP Sgt. Dave Rektor. "I've seen first-hand the result of wheels flying off and killing people."

Rektor recalled an incident from last year when a woman was killed after two wheels flew off a garbage hauler and smashed into her car. The incident happened near a ministry inspection station near Putnam Road, just east of London.

Hundreds of truckloads per week

CBC News reached out to some of the contractors that haul GTA garbage, none of which replied to requests for comment. Experts say most garbage haulers are responsible, and don't wait for the ministry to inspect their trucks. Instead, they do it themselves on a regular basis.

"It's up to the drivers to do trip inspections and monitor their equipment to make sure those defects don't appear," said Kevin Kirkham, a highway carrier safety inspector with the ministry."

Ministry of Transportation highway carrier safety inspector Kevin Kirkham regularly sees the problems with garbage trucks. (Amanda Margison/CBC)

In 2015, Toronto sent 510,831 tonnes of municipal waste to the Green Lane Landfill alone. Other trucks head to dumps elsewhere in Ontario, and still others go as far as Michigan. It amounts to hundreds of trips every week.

Garbage haulers are not the worst offenders: trucks carrying wood and steel have higher rates of inspection failures. But with millions of tonnes of trash moving along Ontario highways every year, police say the risk of accidents involving those vehicles skyrockets.

Garbage haulers under greater stress

Transport trucks hauling loads of trash, which typically weigh in at 34 tonnes, need stiffer maintenance regulations, says Mark Slemin, transportation technology professor at Fanshawe College in London, Ont.

The massive garbage haulers are subject to more stressors than typical transport trucks because of the wear-and-tear they sustain going in and out landfill sites, he explains.

Mark Sleman, transportation technology professor at Fanshawe College in London. (Amanda Margison/CBC)

"These things have to go to a landfill, have their garbage removed, [get] refilled and [be] driven back," ​Slemin says. "You're not just looking at a trailer that's just going to stay in the city or on the roads."

​He regularly sees garbage trucks get stuck or damaged while driving through landfills.

Thirty per cent is a very high safety rate in terms of infractions. - OPP Sgt. Dave Rektor

Debris can often get inside brake chambers or rip brake airlines, which drivers can easily miss and which can lead to issues on the road.

"With mud, debris, garbage, whatever they're hauling," Slemin says, "it is a little difficult to see: brakes out of adjustments, springs, air lines, cracks in the frames."

Kirkham routinely sees problems with garbage trucks, too.

"Brake defects, tire defects — those sorts of defects coming in and out of landfills," he says. "Then they're operating on the highways."