 |  | Securing Trucks with the Right Restraint
You can help prevent dock/trailer separation accidents
with the proper equipment; here's your guide.
Nothing slows or shuts down busy, fast-paced receiving/shipping docks like an accident. And dock/trailer separation is one cause of accidents at the dock that you can help prevent and thereby minimize the associated risks of personal injury and property damage that may result.
Recommended preventative measures include installing a vehicle restraint at each of your dock positions, and then ensuring proper, consistent usage of the restraints.
In this selection guide we'll look at the types of equipment that should enable you to avoid many of these dock/trailer separation accidents. OSHA requires that you secure or restrain all trucks to the dock while loading and unloading. The agency, however, leaves specific details on how to do so to plant and warehouse managers.
But first let's examine why dock/trailer separation occurs. Several factors may be involved. Truck drivers want to get their rigs rolling again, for example. They're in a hurry; time is money. So you need to take positive action to prevent a driver's attempt to make a premature, unscheduled departure.
If a driver pulls away too early then the lift truck and/or operator loading or unloading inside the truck/trailer just might plunge off the dock. Or a worker on foot in the trailer might fall.
More subtle, but no less dangerous is another type of dock accident: It stems from "trailer creep." Creep occurs when the truck/trailer gradually moves forward, or away from the dock due to impacts of a forklift as its shuttles in and out, loading or unloading. Even placing simple wheel chocks against the tires and setting the brakes won't entirely halt creep.
When a semitrailer is parked and detached from its tractor rig and supported at the nose only by landing gear, forklift motion also can cause that gear to collapse. The possible consequences include the forklift, operator, and worker(s) on foot being thrown forward. Trailer tipover creates similar hazards.
There's also a potential hazard at the dock from trailer rigs with air-ride suspensions—when the driver fails to release air from the suspension system once he has spotted the vehicle. As a lift truck operator cycles in and out of a trailer while he is loading or unloading it, this cycling tends to release some of the undumped air in the suspension system. Result: the trailer tends to "walk away" from the dock.
Making sure that the driver dumps the air from the suspension and applying a blocking force against the trailer through use of a vehicle restraint are measures you can take against "walkaway."
100,000 crossings per year
Perhaps you think you can gamble that the chances are slim—a million-to-one or more—that these kinds of accidents will happen. Think again! Consider that at a single dock position, 100,000 lift truck crossings per year is not uncommon.
Here's the math if one has 10 trucks/day loading/unloading 20 pallets = 200 loads x 250 days/year = 50,000 loading operations x 2 crossings per operation = 100,000 crossings annually. Viewed from the magnitude of these figures, the potential for a dock accident becomes more apparent.
Ensuring that your dock workers are well-trained and safety conscious will go a long way toward accident-free receiving and shipping. Promoting clear communication—by using visual (stop and go lights) and audible (alarm) signals—between dock operators and truck drivers will help, too. Selecting proper safety equipment is vital as well.
Several kinds of equipment will restrain trucks. Safety experts don't recommend using one type, simple wheel chocks, however.
These chocks don't have the "muscle" to hold a big rig if the driver really wants to get going again. They slip on ice and wet pavements. And driver or dock worker may forget to place them, or do so improperly.
Instead of simple chocks, there are other, safer methods to more securely anchor trailers to the dock. These methods either apply a restraining force to the over-the-road vehicle's rear impact or underride guard (the ICC bar) or to its wheels.
For nearly 20 years now, the dock equipment industry has taken advantage of the fact that the federal government has required trailers to have this ICC bar at the back of the vehicle. Many dock restraints perform their holding function by hooking, locking, or otherwise applying a restraining force to this ICC bar. Three variations are shown in the drawings on the opening page.
Within this category of ICC-bar devices, there are a number of manually and electrically/ hydraulically-operated vehicle restraints of varied designs.
Most ICC-bar restraints are engineered to hold against a 32,000 lb force; some have even greater pullout holding power.
Due to federally mandated changes in ICC-bar placement and bar dimensions effective January 1, 1998, newer trucks will have a bar that's lower. Ask your restraint supplier if the company's devices meet this Department of Transportation change and will work on both "old" and "new" ICC bars.
Wheel blocking methods
One out of every four trucks arriving at your docks, roughly speaking, can't be secured by an ICC-bar-type restraint, however. The bar may be missing. Or it may have been damaged. Or on certain trucks, such as lift-gate vehicles, the truck's design eliminates the bar. Or the vehicle's bumper design prevents holding by an ICC bar.
For these trucks, restraining the wheels by automatically powered chocking should work—provided you're using the right equipment. Several of the major dock system manufacturers have developed new designs using this approach in recent years. Three variations are shown here in this article.
Planning for flexibility
Cost will be a factor, of course, in your decision to go with one or more of these types of restraints. Depending upon whether an ICC-bar restraint is mechanically (manually) or electrically/hydraulically operated, installed cost per dock position will be in the range of $1500 to $6500. Wheel blocking systems will run higher, or in the range of $8,000 to $11,000 total installed cost.
If your plant or warehouse services a wide variety of trucks and trailers, then you might want to install ICC-bar restraints at most positions, and just have one or two docks equipped with wheel-blocking restraints. This approach offers the flexibility to deal with just about any arriving vehicles. If, however, liftgate vehicles are more the norm, then your choice of restraints will likely lean in the other direction.
No matter which restraint type you choose, they work to their highest degree of safety assurance in tandem with a dock communication system. The dock position should be equipped with an inside and outside "stop/go" light system with audible alarms which integrates with the restraint. Dock system suppliers can provide restraint and master control panel for communication—along with a dock leveler—as a package deal. |
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