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Loading Dock Safety: Education and Equipment can increase safety in your loading dock. By Dave Piasecki It
is easy to come to the conclusion that the loading dock area is very likely to
be the most hazardous part of your operation when you consider the combinations
of hazards and the volume of activities that occur in this area.
For the lift truck operator, ramps and inclines, overhead obstructions,
dissimilar surfaces often wet and slippery, poor lighting in trailers, other
vehicular traffic, pedestrian traffic, restricted views, sheer drops, trailer
creep, congested staging areas, and accumulations of empty containers, pallets,
and debris are hazards which can all be present at the same time within a very
confined area. While OSHA does
require training of lift truck operators on
these types of hazards, many operations fail in providing detailed hazard
assessment, operational procedures, and day-to-day enforcement of safety issues.
In addition, those employees that do not operate lift trucks are rarely
trained on dock safety issues even though they share many of the same risks as
the lift truck operators. The biggest reason to put a priority on dock safety is not so much related to the frequency of accidents in dock areas as it is to the potential severity of injuries that can occur in these types of accidents. Injuries sustained when lift trucks tip over or fall from docks, or those that occur when pedestrians are impacted by a lift truck, falling load, or tractor-trailer, tend to be very serious and sometimes fatal. Prevention of these types of accidents can be achieved through proper equipment, proper training, and enforcement of safe operating procedures.
Wheel Chocks
When
people think of dock safety the first thing that will generally come to mind is
the wheel chock. Wheel chocks are
wedge-shaped blocks placed in front of the rear wheels of a trailer to prevent
the trailer from moving away from the dock while the trailer is being loaded. Trailer creep (also known as trailer walk, dock walk) occurs
when the lateral and vertical forces exerted each time a lift truck enters and
exits the trailer cause the trailer to slowly move away from the dock resulting
in separation from the dock leveler. Factors
that affect trailer creep are the weight and speed of the lift truck and load,
the grade of the drive the trailer is parked on, the softness of the suspension,
the type of transition (dock levelers, dock boards) being used, and whether the
trailer has been dropped off (spotted) or if it is still connected to the
tractor. Separation from the dock
also occurs when a driver prematurely pulls away while the truck is still being
loaded/unloaded. OSHA
regulations require the use of wheel chocks or other vehicle-restraining device
when loading and unloading trucks and trailers.
The effectiveness of wheel chocks is an often hotly debated issue. Depending on the surface conditions and type of chock being used chocks can
sometimes slip thus reducing their effectiveness in preventing trailer movement.
Also, requiring people to walk in between trailers to set and remove the wheel
chocks creates additional safety issues. A
bigger problem with wheel chocks is, however, not so much related to their
physical characteristics as it is to the difficulty in enforcing their use.
Often, companies feel that by chaining wheel chocks to the outside of
their dock and putting up a couple of signs reminding the drivers to use them
they have done their part in dock safety. In
reality this approach will provide minimal if any usage of the chocks.
If you’re going to use wheel chocks you must require your lift truck
operators to verify the chocks are in place, and be prepared to frequently verify
that your operators are doing this. You
should also make sure your operators have an easy way of verifying the chocks
are in place. Many dock designs do
not provide visibility to the trailer wheels from inside the building. Windows, mirrors and cameras can resolve this.
Enforcement of this type of a policy is critical; if you do not regularly
confirm compliance and discipline non-compliance, the chocks will simply not be
used. You also need to keep spare chocks on hand as chocks are
often casualties of theft and snowplowing operations. It's also a good idea to require your delivery drivers to move the tandems all the way back before backing into your dock. This helps to ensure that the trailer doesn't slip forward from the tandems when the wheels are chocked. It also makes the trailer more stable. The delivery drivers may not like this requirement, so once again, enforcement is critical.
Other Vehicle Restraint Devices. There are a great variety of alternative vehicle restraint systems available and their popularity is growing. Of these, one of the most popular is the ICC bar type restraint system. These systems incorporated a device that engages the ICC bar (rear impact guard) on the rear of the trailer preventing it from moving away from the dock. These devices may be mechanically or hydraulically operated and may vary significantly in design and functionality from one manufacturer to another. There are also other types of restraints such as those that automatically engage the rear wheels of the trailer. As with the ICC bar restraints, the wheel engagement restraints also vary significantly from one manufacturer to another. There is not a one system fits all solution for vehicle restraints. ICC bar systems may not work with damaged ICC bars, lift gates, and low-boy trailers. Wheel engagement systems are more expensive and may have problems in northern climates due to snow or ice.
Dock Levelers It’s
also important to note the importance of the dock leveler in dock safety.
Dock levelers provide a bridge to the trailer as well as a ramp to
facilitate the transition in height from dock to trailer.
Dock levelers are rated by weight capacity and by the service range.
The service range also known as the height differential rates the safe
range above and below dock level you can use the leveler to transition to the
trailer height. Differences in
trailer width, height, floor level and the recent popularity of air-ride
suspensions are forcing more attention on the functionality of dock levelers and
their ability to safely handle the variety of vehicles serviced. Dock
levelers come in mechanical and hydraulic models. The mechanical models require
the operator to pull a chain and then walk down on the leveler to engage it,
while hydraulic models provide automatic functionality from push buttons usually
mounted on the wall next to the dock door.
Hydraulic models also offer a smoother transition when entering vehicles
with soft suspensions (such as air-ride). Mechanical levelers use a mechanical
safety mechanism to prevent the dock from bottoming out if it disengages from
the trailer floor, the side-effect of this safety mechanism is that when you
enter a trailer with a soft suspension the main portion of the leveler will not
always drop with the suspension, leaving only the hinged lip to make up for the
height differential. Hydraulic
levelers incorporate a hydraulic velocity fuse as a safety mechanism, this still
allows for full functionality of the leveler as the trailer height changes. The advantages in using automatic dock equipment with electronic controls include the ability to incorporate all of the equipment into signaling devices. Signaling devices such as signal lights will let your lift truck operators know that the restraint mechanism and the dock leveler are properly engaged signaling that it is now safe to enter the trailer, while at the same time signaling the truck driver that it is unsafe to pull away from the dock.
Additional Equipment Other
dock equipment includes stand-alone barriers and barriers built into dock
levelers to prevent driving off the edge of the dock when the dock is empty,
fixed and variable height ramps to raise trailers to a level closer to that of
the dock, and a variety of dock doors and dock seals.
It’s very important to use the operating instructions provided by the
manufacturer of dock equipment as operating procedures will vary based upon the
type of equipment used. Some
hydraulic dock levelers may allow you to leave the leveler engaged as the
trailer departs while most mechanical levelers should be fully disengaged and
returned the stored position prior to trailers departing.
Additional Recommendations The
following are additional recommendations that can improve safety in your dock
operation. Some of these are
equipment related while most are simply procedural.
Also
read my article on Lift Truck Safety and see
the Dock Equipment Pics page.
Dave Piasecki, CPIM is owner/operator of Inventory Operations Consulting LLC, a consulting firm providing services related to inventory management, material handling, and warehouse operations to manufacturers and distributors in Southeast Wisconsin and Northeast Illinois. He has over 15 years experience in warehousing and inventory management and can be reached through his website (http://www.inventoryops.com), where he maintains additional relevant information and links Copyright
© 2001,
2002, 2003
Inventory Operations Consulting LLC
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