Safety is a concern in any part of a facility, but there is one area that typically worries managers the most: loading docks.
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In today’s fast-paced environment, the loading and unloading of semi-trailers can pose risks for everyone from forklift operators and dock attendants to service technicians and bystanders. In fact, roughly 34,900 people are seriously injured and 85 killed every year in forklift-related incidents in the U.S., according to OSHA. Unfortunately, there is no one-size-fits-all solution to this problem since no two facilities—or no two dock stations—are exactly the same. However, the lynchpin in any dock safety system is the vehicle restraint.
Old-Fashion Wheel Chocks
One of the most common loading dock accidents happens when drivers mistakenly drive away while a forklift is still inside the trailer, which is called early separation. Another common problem is “trailer creep,” which occurs when trailers (particularly those with air-ride suspension) gradually move away from the dock due to the ongoing impact and momentum of forklifts traveling in and around them.
In both cases, the first step in accident prevention is to secure the trailer to the dock using a locking device on either the trailer’s rear impact guard (RIG) or rear wheel. Many loading docks still use old-fashion wheel chocks in front of trailer tires as a means of restraint. However, multiple problems can come with this including: insufficient pullout resistance, chock slippage, and the time and safety concerns related to placing them by hand on the busy drive approach. Additionally, chocks have no embedded communication system to let the truck driver, lift driver, or dock personnel know they are in place.
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RIG-based manual or automatic restraints can use a vertical barrier or a full rotating hook to lock onto the trailer’s RIG. They are designed to help prevent all types of trailer separation, including early departure, trailer creep, trailer tip-over (from landing gear collapse), or trailer up-ending. Most also incorporate full-time communication systems that indicate when they are properly engaged and it is safe to load and unload.
The most basic type of RIG-based system is a vertical barrier restraint. Vertical barrier restraints provide solid, dependable upward pressure to RIGs, helping to address the most common trailer separation accidents. They can be wall-mounted, ground-stored, or use a recessed design that stores beneath the dock leveler pit.
Rotating hook restraints are generally considered the industry-leading standard for vehicle restraints. As their name implies, they employ a rotating hook that swings up and around the RIG, utilizing the energy of the backing trailer.
Unfortunately, conventional RIG-based restraints do not work in all situations. For example, docks that handle a large volume of trailers with hydraulic gates (such as retail, beverage, and grocery industries) typically cannot use them as those gates block access to the RIG. Likewise, facilities that regularly handle trailers with damaged RIGs or RIG obstructions (such as axle-wide splash guards) cannot use them, nor can dock facilities in foreign countries where RIGs are not standardized or required. International shipping container (intermodal) chassis traffic is another consideration, since these chassis also commonly have RIG obstructions.
Fortunately, there are RIG-based restraints that can alleviate this problem. These models incorporate a “shadow hook” to form a secondary point of engagement on the RIG, helping to secure the chassis to the dock and providing an additional layer of safety when dealing with rear-impact guard obstructions. When these restraints are activated, their hook attempts to wrap around the rear-impact guard. If the hook comes in contact with a rear-impact guard obstruction, the shadow hook pivots to secure the trailer in place. If the trailer moves, the shadow hook locks in the safety stop, which helps prevent a wide variety of trailer separation accidents.