TORONTO, Ont. – Efforts to secure cargo tend to focus on such things as straps and chains, but North America’s new load security standards are also focusing evermore attention on a tool of a different sort – rubber friction mats.
Friction, after all, is the ultimate force that keeps a skid, roll or drum from sliding across the deck of a trailer in the first place, and friction mats have long been used to limit the movement of everything from rolls of paper to drums of hazardous waste.
The only difference is that enforcement officers are also beginning to recognize their powers.
“There’s recognition now that one or two types of mats do offer the type of coefficient of friction the regulations ask for,” says Russell Bula, vice-president of sales and marketing for Toronto-based NRI Industries, which manufactures LoadGrip rubber mats from recycled tires.
Without a mark showing its working load limit (WLL), a friction mat is considered to offer resistance equal to 50 per cent of the weight of the cargo sitting on top of it.
“But our struggle has been to have transporters recognize that there’s more (to consider) than just coefficient of friction (COF),” he adds.
Picture, for example, the mesh-like pad used to hold a household carpet in place. It may offer the required COF or grip, but it would be shred to pieces under a pallet of freight.
“The material has to be able to stand torsional grinding and shearing,” Bula says, referring to stresses found inside a moving trailer.
“Typically, the straps that are often there try to increase the amount of friction a skid or load has on the floor: you’re putting a great deal of load on the rubber mat.”
Rubber mat suppliers ranging from Dodge-Regupol to NRI and Amorim Industrial Solutions each have their own ways of adding strength to the material. NRI, for example, incorporates a special fiber; the other companies mix rubber into polyurethane. A stamp of approval from the American Association of Railroads can also be a helpful tool for determining whether a mat is up to the job.
“And I’ve come to believe that if it will survive an AAR test (for intermodal and boxcar applications), there’s probably very good correlation with over-the-road,” Bula says.
Friction mats are not for every fleet. Less-than-truckload operations tend to avoid mats because they can add a significant amount of time to loading procedures that normally involve sliding skids into position, says Rolf VanderZwaag of the Ontario Trucking Association.
But the addition of mats (and every other load securement device at your disposal) could become particularly important in jurisdictions like Ontario, which has opted out of a preamble to the National Safety Code regulations that allow loads to shift a minimal amount, as long as the movement doesn’t affect the stability of a trailer.
And enforcement officers in jurisdictions such as New York State are reportedly paying more attention to the way cargo is secured inside van trailers.
“Enforcement officers are looking for certain visual things, and whether there has been some effort to secure (the load),” VanderZwaag adds.
“But they won’t give any specifics about the kinds of things they’re looking for.”
At the very least, the friction mats would demonstrate that a carrier has attempted to secure cargo in place.
The combined strength of the restraints used to secure any load needs to withstand a force of 0.8 g in a forward direction and 0.5 g from side to side, although enforcement officers in the U.S. have suggested that they’re willing to accept half that.
It’s also important to remember that friction mats – typically available in single sheets or rolls as much as 1,000 feet long – are designed to stand up to single trips. They’re a disposable commodity.
While nobody needs to line the entire floor of a trailer with the material, carriers should take care to follow the procedures outlined under the load security regulations, Bula adds.
When holding rolls of paper in place, for example, the mats need to extend beyond the load by four to five inches in the directions that they’re supposed to keep the roll from sliding.
Fleets should also consider their own tests, loading, measuring and monitoring any movement in a minimum of 25 loads to ensure any cargo securement devices are working as they should, he says.