We need to talk about dock shock

Coined by Caljan Rite-Hite, the term dock shock describes an unsafe situation that occurs during the process of unloading and loading trailers.

Dock shock is the jarring that occurs when a forklift truck crosses between the warehouse floor and the trailer bed, caused by the bumps and gaps that exist on traditional dock levellers. Dock shock is a source of vibration, a known serious health risk.

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 loading bay equipment.

At virtually any traditional loading bay configuration, forklift 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 bay, is often associated with forklifts. According to documented reports, back disorders are more prevalent and more severe in forklift operators exposed to WBV compared to non-exposed operators. The International Organization for Standardisation (ISO) has issued various guidelines for vibration exposure levels. ISO 2631-2:2003, for example, outlines acceptable vibration standards. The European community has also taken notice issuing Directive 2002/44/EC to provide minimum health and safety requirements regarding worker exposure to vibration risks.

Loading bay equipment: a contributor
For years, the forklift industry has worked to address problems associated with WBV. Innovations designed to minimise vibration include pneumatic tyres, contoured and pivoting seats, vibration-dampening engines, anti-vibration seats, and advanced seat-suspension systems and seat cushions. However, many studies indicate that loading bay 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.

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 forklift trucks and their interaction with trailers are key.

Dock levellers serve as a bridge between dock floor and semitrailer. Vehicle restraints are devices that lock in between the trailers back wheels to prevent separation from the dock during loading and unloading. Restraints help to prevent a variety of catastrophic accidents.

Developed on the basis of its research, Rite-Hite’s rear hinge dock levellers provide smooth transition between loading docks and trailers, preventing injuries and minimising lift truck and product damage.

When analysing the interaction of vehicle restraints and trailers, Rite-Hite found that unstable trailer beds move vertically, or drop, due to the weight of forklift 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 forklift truck operators to experience significant jolts. Rite-Hite’s vehicle restraints help prevent trailers from moving up and down, maintaining consistent trailer bed height.

The severity of dock shock varies from dock to dock and industry to industry. But there is little doubt that it exists at any facility that operates loading docks and forklift truck equipment. The first step toward protection is to realise that the issues are relatively commonplace.

Given the magnitude of the safety risks involved and the employers responsibility to control the environment where forklift trucks operate, it is worthwhile to have a trained loading bay equipment specialist inspect your dock situation to assess the severity of dock shock and the risks involved. If the problem warrants attention, don’t overlook technology. Some dock levellers and vehicle restraints are now designed specifically to minimise 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.