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Why Loading Docks Need Vehicle Restraints

Before automatic vehicle restraints existed, trailer separation accidents at loading docks across the world were fairly common occurrences. Product was damaged, deliveries were delayed or missed, and – worst of all – workers were seriously injured or even killed.

For a long time, these hazards were a known risk to the job. Wheel chocks helped mitigate some of these disasters but were not mandated by OSHA until 1978. Unfortunately, they were not consistent in preventing common trailer separation accidents like like trailer creep, trailer pop-up/up-ending, landing gear collapse, and early departure.

It all changed with the introduction of the original Dok-Lok® vehicle restraint in 1980.

The Original Dok-Lok

The simple – yet effective – design of the world’s first rotating hook vehicle restraint established the industry standard for loading dock safety. The Dok-Lok design secured semi-trailers to loading docks by wrapping around the Interstate Commerce Commission (ICC) bar, which is now called the rear-impact guard (RIG). In doing so, the Dok-Lok helped prevent common trailer separation accidents – notably “trailer creep” and “dock walk,” which occur when the loading and unloading action push a trailer away from the loading dock opening.

Rite-Hite’s “rotating hook” concept brought a new level of safety to loading docks and effectively launched the vehicle restraint industry. OSHA agreed, formally recognizing the Dok-Lok as an alternative means to its wheel chock standard (29 CFR 1910.78) in 1981.

Common Trailer Separation Accidents

There are five accidents that occur at the loading dock due to inadequate trailer restraint methods.

  1. Trailer Creep (Dock Walk). The trailer gradually moves away from the dock due to the repeated momentum created by the forklift traveling in and out of the trailer with sudden starts and stops. Eventually the leveler lip loses contact with the bed of the trailer and a dangerous gap results between the trailer and dock. Air-ride trailers compound the problem.
  2. Early Departure. The truck driver mistakenly pulls away from the dock before loading operations are complete. Oftentimes this is due primarily to lack of communication between truck driver and dock workers. Light communication at the dock helps mitigate this as well.
  3. Landing Gear Failure. Weak or corroded landing gear give way under the impact of loading and the nose of a spotted trailer collapses to the ground, forcing the rear of the trailer, and the RIG, up vertically, and away, horizontally from the loading dock. If not secured, this accident can cause the trailer to tip over, and create a cascading “domino effect” as trailers one by one, are knocked into the adjacent trailer.
  4. Trailer Upending. Often occurring with pup trailers, where the first heavy load placed in the nose of the trailer causes the rear of the trailer to rise, forcing the rear of the trailer, and the RIG, up vertically, and away from the dock.
  5. Trailer Pop-Up. A heavy load on the rear of an empty (or near empty) trailer causes the rear of the trailer to be forced toward the ground, popping the nose of the trailer in the air.

How Dok-Lok Innovations Improved Loading Dock Safety Through the Years

Vehicle restraints have received a number of upgrades throughout the last four decades. For example, when the first RIGs were mandated by NHTSA in the 1990s, a new “fish hook” design helped better secure these types of trailers.

Restraints that use hydraulic cylinders were developed in response to the surge of air-ride suspension trailers. Hydraulic restraints proved effective at controlling the increased horizontal and vertical movement that occurs during loading and unloading of air-ride trailers. By keeping trailers secured to the loading dock, hydraulic restraints helped prevent loading dock accidents and, simultaneously, helped reduce the opportunity for contamination by eliminating gaps that might be created due to the trailer shifting.

The past decade has seen even more innovation in vehicle restraint technology. For instance, a rotating hook Dok-Lok featuring a secondary “shadow hook” was introduced in 2012. This addressed the need for facilities to secure intermodal chassis trailers and trailers with obstructed RIGs, as well as traditional trailers. Additionally, advanced restraints are now built with an auto re-fire feature for additional safety in the case of trailer movement – as well as to deter tampering with trailers already secured at the dock.

Wheel-based Restraints

Vehicle restraints take different forms for different applications. Because many trailers don’t have RIGs, wheel-based restraints can be an effective option to keep vehicles safely in place during loading/unloading.

Wheel-based restraints are mounted to the ground where trailers back toward the loading dock and engage a vehicle’s rear tire. Models like the Global Wheel-Lok use a 20-inch tall barrier. The GWL-2300 can secure virtually any trailer with tire diameters ranging from 30 to 44 inches. Models such as the GWC-1000 Global Wheel Chock services a wide variety of trailers from specialty to lift gates and intermodal with the added advantage of maintaining effective light communication.

Every Loading Dock Needs Vehicle Restraints

Vehicle restraints are an effective way to protect product, equipment, and – most importantly – workers. It is important to know, they are also mandatory for loading docks that service trailers. Depending on the needs of the facility and the types of trailers that visit, it’s essential to find the right vehicle restraint for your application.

It’s About Safety

Loading docks have the potential to be a very dangerous place. When a truck is left unsecured during loading and unloading, the risk of trailer separation accidents leaves the safety of your employees to chance. Vehicle restraints are a mandated, effective way to protecting your most valuable assets - your employees.

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