A first-time back injury can cost as much as $10,000 when drugs, doctor visits, and physical therapy are factored in. And it gets worse. According to a recent study published by Ohio State University, severe back injuries that occur when a person is hurt over and over again can cost as much as $300,000.

Whether it's a first-time incident or an ongoing problem, facility decision makers need to protect their employees against the potential for chronic spinal injuries. This includes focusing attention on dock shock and trailer drop -- two emerging safety issues that pose serious health and safety risks and adversely affect the profitability of virtually every facility with a loading dock. The National Institute of Occupational Safety and Health (NIOSH) reports that shock (jarring and jolting) causes 36% of all head, neck, and back injuries associated with mobile equipment operators. The National Safety Council reports that one-fourth of all U.S. workplace illnesses and injuries are back related. And the American Society of Orthopedic Surgeons identifies back injuries as the most costly medical condition in America. All told, it's estimated that back injuries cost U.S. companies billions annually.

Here's what every decision maker needs to know about dock shock and trailer drop, as well as advice on to how to protect against the problems they create.

Dock Shock and Trailer Drop Defined

Coined by Rite-Hite, these terms describe unsafe situations that occur during the process of unloading and loading semitrailer trucks.

Dock shock is the jarring that occurs when a lift truck (stand-up walkie or forklift) crosses between the warehouse floor and the trailer bed, caused by the bumps and gaps that exist on traditional dock levelers. Dock shock is a source of vibration, a known serious health safety risk.

Trailer drop describes vertical trailer bed movement or "drop," due to trailer suspension systems, that occurs with the weight of lift trucks traveling in and out. Lift truck operators experience significant jolts from trailer drop, which can lead to chronic back and neck injuries.

Rite-Hite began to research the issues in 2001 when customers expressed concerns about the adverse effects of jarring and jolting on the health of forklift drivers. Facility decision makers have also voiced concern about the negative impact on product and dock equipment.

A Common Problem

At virtually any traditional loading dock configuration, lift truck operators encounter significant jarring and jolting as they transfer materials within a facility's shipping/receiving/staging area and move in and out of trailers. This area is often referred to as the Material Transfer Zone (MTZ).

Jarring and jolting within the MTZ are closely tied to occupational vibration, of which there are two types: segmental, such as hand-arm; and whole-body vibration (WBV), which is transmitted to the entire body through supporting surfaces, such as the legs when standing and the neck, lower back, and buttocks when sitting.

WBV exists in many environments, but at the loading dock, is often associated with forklifts. According to documented reports, back disorders are more prevalent and more severe in forklift operators exposed to WBV vs non-exposed operators. The International Organization for Standardization (ISO) has issued various guidelines for vibration exposure levels. ISO2631/1, for example, outlines acceptable vibration standards. The European community has also taken notice, in 2002 issuing Directive 2002/44/EC to provide minimum health and safety requirements regarding worker exposure to vibration risks.

Loading Dock Equipment: A Contributor

For years, the forklift industry has worked to address problems associated with WBV. Innovations designed to minimize vibration include pneumatic tires, contoured and pivoting seats, vibration-dampening engines, antivibration seats, and advanced seat-suspension systems and seat cushions. However, many studies indicate that loading dock equipment -- not just forklifts -- contribute to WBV and chronic injuries at the loading dock.

Key problem factors within the MTZ are the warehouse floor surface, as well as undulations and sudden, unexpected movements or loads. Published reports show that the amount of vibration transmitted to lift truck operators is primarily a factor of how smooth the driving surface is.

Researchers also suggest that sudden changes in elevation, such as when entering/exiting a rail car, result in harmful high impact loads, and that special attention should be paid to the design of entry points into trailers. In addition, bridges used to span the space between dock and trailer (or rail car) should be designed to minimize shock, especially if the dock is higher/lower than the trailer floor. (Illustrated here, the STR-4000 Dok-Lok, part of the Rite-Hite Smooth Transition Dok System, is a restraint that stabilizes vertical trailer movement.)

Shedding Light On the Issue

No single culprit is responsible for jarring and jolting at the dock, which is one of the primary reasons why the problem has gone unchecked. The dynamics of lift trucks (both forklifts and stand-up walkies) and their interaction with semitrailer trucks are key.

Dock levelers serve as a bridge between dock floor and semitrailer. Vehicle restraints are devices that latch onto a trailer's Rear-Impact Guard (RIG) to prevent separation from the dock during loading/unloading. The restraints help to prevent a variety of catastrophic accidents.

Research showed that a lift truck experiences significant jarring as it encounters bumps and gaps found on standard dock levelers during the loading and unloading process. Subsequent Rite-Hite studies showed conclusively that dock shock is a significant source of vibration.

When analyzing the interaction of vehicle restraints and trailers, Rite-Hite found that unstable trailer beds move vertically, or "drop," due to the weight of lift trucks traveling in and out. Trailers with air-ride suspension systems float up and down to maintain a consistent trailer height when loaded or unloaded, causing lift truck operators to experience significant jolts.

Trailer drop also contributes to product damage. As a lift truck enters a trailer, fragile loads can be damaged or even fall off the pallet, if not properly secured. Driving forklifts over unstabilized, steeply inclined levelers and bumpy terrain also accelerates wear on brakes, tires, transmission, steering axle, and other components. The situation is also hard on dock levelers, seals, shelters and bumpers. The cost for repairs to a single dock seal as a result of trailer movement can be as high as $2,000. And productivity is hampered because lift trucks need to slow down to avoid problems created by dock shock and trailer drop.

Taking the Right Approach

The severity of dock shock and trailer drop varies from dock to dock and industry to industry. But there's little doubt that they exist at any facility that operates loading docks and lift truck equipment. The first step toward protection is to realize that the issues are relatively commonplace.

Given the magnitude of the safety risks involved and the employer's responsibility to control the environment where lift trucks operate, it is worthwhile to have a trained loading dock equipment representative inspect your dock situation to assess the severity of dock shock and trailer drop and the risk involved. If the problem warrants attention, don't overlook technology. Some dock levelers and vehicle restraints are now designed specifically to minimize these conditions and create a smooth transition between the warehouse floor and the trailer.

Understanding these new chronic safety issues and taking a proactive approach will provide a safer, more profitable loading dock.