News | May 3, 2000

Dangers at the Dock

Source: Rite-Hite Corporation
Three safety concerns to address now (and seven more that need your attention)

Rite-Hite Corporation
Appeared in March 1999 issue of Occupational Health & Safety

The loading dock at ACME Industries had been accident-free for more than a year. The work crew was experienced. The facility had just passed a complete OSHA inspection, which found the dock in full compliance.

None of that mattered on the snowy morning when a truck edged away from the dock just as a forklift was entering.

The truck bed rested six inches below dock level after the driver exhausted the trailer's air suspension. The forklift, coming down the steeply inclined dock leveler, had repeatedly jostled the trailer, and the wheel chocks on the slick, snowy pavement outside had not held.

Finally, coming down the ramp with a 1,000-lb. load, the forklift pushed the trailer another inch out from the building. The leveler's lip dropped off the trailer bed, and the forklift tumbled into the gap between trailer and dock, taking the driver with it.

Every year, accidents like this happen on loading docks, putting forklift drivers at risk of crippling or fatal injuries. Often, the docks involved are fully OSHA-compliant. Just one such accident can cost an employer $1 million or more in workers' compensation, product and equipment damage, lost producitivity, higher insurance premiums and liability.

The risk of such accidents is growing as the economics of the trucking industry drive trailer-design changes that make servicing at traditional loading docks more difficult. In response, many warehousing and safety managers are reviewing their dock equipment and dock operating practices. (Click here to see a sidebar on dock safety checks.)

Special Challenges
The loading dock has always presented special safety challenges. Forklifts must place cargo on truck trailers not physically attached to the building and not under the control of company personnel. To enter the truck, the forklift must cross a dock leveler that bridges a four-foot drop from floor level to driveway.

On an average loading dock, forklifts cross the gap between building floor and trailer roughly 100,000 times per year. Serious accidents can happen if a truck separates from the dock while a forklift is entering or backing out. But even when no truck is present, the dock edge poses a significant hazard. Forklifts can fall off vacant dock positions, in some cases crashing straight through a closed overhead door.

How often do these accidents happen? OSHA's "First Report of Serious Accidents," looked at 229 forklift incidents from 1985 to 1990. OSHA found that 3.1 percent of the accidents happened while forklifts were loading unchocked trailers, and that 7.0 percent involved forklifts running off a loading dock or other surface. That means more than 10 percent of serious forklift accidents potentially involve the drop-off at the dock edge.

The OSHA report covered only accidents that, because of their severity, required complete reports. Many less serious accidents go unreported; other incidents qualify as "near misses" in which no one was hurt, though a calamity was barely avoided. All told, industry sources estimate that 25 percent of industrial accidents happen on loading docks.

Safety at the dock edge
Dock safety starts with keeping trailers securely in place during loading and unloading. Trailers can separate from the dock in three basic ways:

  1. Unscheduled departure. A truck driver, misunderstanding instructions and unable to see or communicate with dock personnel from outside the building, pulls away from the dock while a forklift is crossing the dock leveler or inside the trailer.
  2. Trailer tipover. A trailer detached from its tractor is parked at the dock with its front end supported by landing gear. Forklift traffic rocks the trailer, its landing gear collapses, and the trailer tips on its side or pitches forward on its nose.
  3. Trailer "creep." The repeated impact of forklifts moving in and out causes the trailer to inch away from the dock until the leveler lip loses contact with the trailer bed.

Two new trends in trucking make "trailer creep" more pronounced. First, trucking companies, striving to retain drivers by making them more comfortable, are switching rapidly to trailers with air suspensions. If a trucker parks a trailer with the air suspension still inflated, the trailer bounces as the forklift enters and quickly edges out from the dock -- a condition called "trailer walk."

If the trucker deflates the air suspension before loading -- the correct practice -- the trailer bed may drop to as much as 8 inches below dock level. Forklifts descending the ramp strike the trailer bed much more forcefully than if the grade were level and push the trailer away from the dock -- a condition called "ski-slope effect."

Low-profile truck tires, another industry trend, also create "ski-slope effect." Today's trailers may come equipped with tires as small as 19.5 inches in diameter. The net result is trailer beds positioned several inches below standard dock height.

The trouble with wheel chocks
Trailers held in place only by the OSHA-mandated method -- wheel chocks -- are always at risk of separation. Chocks are useless on snowy or icy pavement. They get lost, stolen or swept away by snowplows.

Chocks are also inconvenient to use. Consider chocking a trailer on a rainy day. The dock attendant must find a raincoat, walk to a door (often at the far end of the dock), descend a wet stairway, navigate around parked trailers to the correct dock position, locate and place one chock, walk entirely around the trailer to the other side, place the second chock, then walk back into the building -- all in a downpour. Is it any wonder workers sometimes neglect chocking?

But even if used consistently and as designed, wheel chocks do not hold trailers securely. Chocks are no match for a semi rig with a 400-horsepower engine. Furthermore, chocks provide no communication link to tell the truck driver when it is safe to depart and to tell forklift drivers when it is safe or unsafe to enter the trailer.

Secure restraint
An alternative to wheel chocks -- recognized by OSHA -- provides effective restraint for trailers and helps prevent all types of accidents involving separation from the dock. Vehicle restraint systems physically hold the trailer in place, usually by grabbing the rear impact guard (also called the ICC bar). The devices include a communication system of lights and signs inside and outside so that truckers and dock attendants always know whether the trailer is secured.

When the truck backs into position, a dock attendant presses a button to activate a restraining bar or hook. Hook-type restraints tend to be more effective because the hook "wraps around" the rear impact guard, thus keeping the bar from moving not only outward (away from the building) but also upward.

For example, if a trailer's landing gear collapses and its front end drops, the rear end will move up. A hook-type restraint will stop the upward movement by holding the rear impact guard in place, keeping the trailer upright and preventing a serious accident.

Once the device engages the trailer, a light outside the dock flashes red, telling the trucker not to pull away. Inside the dock, a light flashes green, telling dock personnel that it is safe to load the truck.

When dock personnel have finished with the truck, an attendant presses a button to deactiveate the restraint. The light outside changes to flashing green, telling the trucker it is safe to leave. Inside, the light changes to flashing red, telling forklift drivers to stay out of the truck.

Vehicle restraints can securely engage more than 95 percent of trucks and trailers. For the rest -- such as drop-frame trailers or trucks with hydraulic lift gates -- wheel restraints are an effective alternative. When the truck is in position at the dock, an attendant presses a button to activate a barrier that fits snugly against the tires. Vehicle restraints have been on the market since 1980, yet some 75 percent of loading docks still do not use them. Adding restraints can substantially reduce the risk of serious dock accidents.

A barrier at the brink
Barriers at unoccupied dock positions can finish the job of protecting forklift drivers from perilous falls off the dock edge.

There are many ways in which forklifts can tumble from docks: The floor is wet and slippery, brakes fail, the accelerator sticks, the steering malfunctions, or the forklift driver simply makes a mistake and backs up too far in turning around after exiting a trailer.

An effective remedy is a retractable gate at the dock edge, either mechanically or electrically operated. An even better solution is a hydraulically powered dock leveler with a special lip that extends upward when the leveler is in its stored position.

The extended-lip leveler has the advantage of forming the barrier automatically -- no one has to remember to close a gate. When a truck leaves after servicing, the leveler recycles to dock level with the lip reaching several inches above the floor. In testing, the
barrier created by the leveler lip has consistently withstood the impact of a 10,000-pound forklift traveling at up to 4 miles per hour.

Investing in safety
With the safety equipment available today, there is no reason forklift drivers should face the risk of falling from a loading dock. Vehicle restraints and dock-edge barriers are investments not just in accident prevention but in a more profitable operation.

E.I. DuPont documented savings of $2,000 per year at every dock position just by eliminating the time and expense of wheel chocking in favor of vehicle restraints. On top of those savings, a safer loading dock means higher employee morale and a more productive workplace.

Vehicle restraints and barriers at unoccupied docks help prevent the most serious kinds of forklift accidents, but there are other hazards to watch for -- all easy to correct. Here are eight common dock safety concerns:

  1. Avoid the "hole in the floor." Some dock levelers stay in a depressed (below floor level) position after they are used to service trailers lower than dock height. This creates a hazard for forklifts driving across the dock. Train employees to return levelers to their normal stored position after use. Or, better yet, install levelers that automatically recycle to floor level when the truck leaves. This feature is available in both hydraulic and mechanical levelers.
  2. Check leveler features. When buying or replacing dock levelers, consider features like automatic safety stops to prevent ramp free-fall, an emergency stop button (for powered units), and toe guards to eliminate a hazardous "pinch point" as the leveler platform descends.
  3. Support spotted trailers. Support the front ends of spotted trailers with trailer jacks. This practice greatly enhances stability and helps prevent tipovers. OSHA recommends it.
  4. Keep weather out. Rain, snow or dirt blowing onto the dock can make the floor slippery, causing not just forklift accidents but nasty spills for pedestrians. A properly sized dock seal or shelter can keep the floor clean and dry, and comfortable in hot or cold weather. For docks that slope back toward the building, specially designed header seals can keep water from funneling down the top of the trailer and into the work area.
  5. Keep them working. Vehicle restraints and dock levelers are not high-maintenance items, but they do need some care. Planned maintenance according to the manufacturer's guidelines is essential. If any piece of equipment malfunctions, take it out of service and fix it promptly.
  6. Be safe down under. Personnel fixing or maintaining a leveler and working underneath should support the unit with a safety strut. The ideal strut supports both the ramp and lip, and provides lockout capability to comply with OSHA.
  7. Check outside. Keep dock approaches free of ice. Pay special attention to outdoor stairs leading down to the driveway -- keep them clean and ice-free.
  8. Remember ergonomics. The repeated stress and strain of activating and "walking down" mechanical dock levelers can cause back and other muscular injuries, as well as add to fatigue. Hydraulic dock levelers position themselves automatically at the touch of a button.

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