COLEMAN, P. E. I. –Many work sites pose a two-pronged safety hazard to dump truck operators: uneven surfaces which create ideal conditions for a rollover and high-voltage overhead wires which can electrocute a driver if he contacts them with the box.

Perhaps that’s why there seems to be an increasing interest in the concept of live bottom trailers, which use a conveyor system to unload material out the back of the tub, eliminating the need to raise the box.

Darrin Mitchell, president of live bottom trailer manufacturer Trout River Industries, said the market is growing by 25% per year. It’s being driven mostly by safety concerns, and some tenders are now even specifying a preference for live bottom trailers.

In Canada, there are three manufacturers of live bottom trailers. Trout River began building the trailers in 1999 to address growing concerns about dump truck rollovers.

Raglan Industries began building live bottom trailers at around the same time, and now focuses on more rigorous applications, such as off-road northern mining operations. Trailers ABS, based in Quebec, also produces the trailers. In the US, the biggest player is Red River.

However, you can trace the concept back much further than the late 90s.

“For us on PEI, it has been around for a long time in potato boxes,” said Mitchell. “However the design has changed greatly in the last 10 years. The trailer has become much more robust to haul big loads for a variety of applications.”

Trout River’s Mitchell said his company first began building the trailers for lime haulers, who were rolling over while unloading the wet, sticky substance.

“Live bottom trailers these days haul just about anything,” said Mitchell. “The most unique I’ve seen is one customer who is using the trailer to haul cow hides from an abattoir to a curing facility. They park the trailer in the building and use it as a hopper to unload the product onto the processing conveyors.”

In Trout River’s case, the trailers are designed mostly for aggregate products six inches in diameter or smaller. Raglan’s heavier-duty offerings are better suited for larger rocks and boulders.

The concept has gained attention right across Canada. They are being used on Olympic-related construction work on the West Coast; in the Alberta tar sands; in northern Ontario mines; and to haul gypsum in Newfoundland. You may also have seen them at work along Hwy. 401 over the past couple years, where they were being used to lay asphalt.

“They would arrive on the site, trip the tailgate, engage the conveyor and keep driving while they unloaded,” explained Mitchell, who spent some time observing his trailers at work along a stretch of 401 between Windsor and London. “They did this all day long while the grader leveled it out.”

Various attachments are available which help control the unloading.

“With all the attachments you can put on the rear to make them more versatile, it’s come to the point where your imagination is the only thing that limits what you can do with them,” said John Michel, president of Raglan Industries.

A shouldering attachment, for instance, can spread the material to the side, along the shoulder of a road. A spreader attachment on the other hand can more accurately control the dispersal of the material, allowing for a smooth layer of gravel to be applied behind the trailer.

Naturally, the added complexity of the trailers does require additional maintenance.

“Any time you have a unit with more moving parts, maintenance becomes more of an issue,” admitted Michel. “You have your sprocket chain, belt, motor, gearboxes and valves and all those require attention. Like anything, it’s as good as the weakest link.”

Trout River’s Mitchell said “We have specifically designed the trailer to have off-the-shelf parts when the time comes for maintenance. You don’t have to wait six weeks to order a special part.”

He said maintenance is pretty straight-forward on his company’s conveyor systems.

“All we ask from our operators besides regular maintenance is that they oil the conveyor chain on a regular basis and they don’t drop boulders in the trailer,” he said.

Live bottom trailers are naturally heavier than traditional dump bodies. However, Mitchell said customers in Ontario are still hauling payloads of up to 39.5 tonnes on a four-axle trailer.

Extreme weather does pose some issues, but most of them have been resolved, Mitchell said. If it’s -30 C, customers will sometimes put a liner in the tub.

The clip-in liners are being used in Fort McMurray, Alta. and also in James Bay.

Michel said Raglan has addressed cold weather challenges by widening the belt so it’s less likely to freeze up. A conventional belt would be as narrow as 32-inches, he said, noting Raglan’s trailers have belts up to seven feet in width.

The ability to operate problemfree in the winter allows customers to run year-round – well beyond road building season.

“In the summer, the trailer hauls asphalt, in the spring it hauls fertilizer, in the fall it hauls top soil to septic beds and in the winter it fills up salt and sand domes,” explained Mitchell.

That versatility is allowing customers to justify the higher purchase price, which could be as much as $15,000 more than a traditional dump trailer, according to Raglan’s Michel.

Manufacturers expect to see interest in live bottom trailers continue to increase, given the safety benefits as well as the ever-increasing versatility of the trailers.

“In ’99, there was a presence. In 2000-2004 there was a really massive change,” recalled Michel. “You see people somewhat doubtful, then accepting them and next thing you know they’re buying them. They’re not quite as popular as the dump trailers, but they’re getting there.”