Loading docks, trailers and rail cars

The loading dock is where lift trucks meet road trailers, rail cars, dock levellers, open edges and people from other companies. It concentrates many of the hazards in this course into a small space: trucks driving onto a surface that can move, falls from the dock edge, pedestrians who do not work at the site, poor lighting inside trailers and time pressure from shipping schedules. This lesson covers the hazards at docks, the controls for trailers and rail cars, dock equipment, and the communication systems that keep drivers and operators working together.

How dock incidents happen

Several of these happen without any obvious warning to the operator. A trailer that creeps away does so a little at a time. A driver in the cab may be unable to see whether a truck is inside the trailer. That is why dock safety relies on positive controls that physically hold the trailer, and on communication systems that do not depend on people shouting.

Securing road trailers

Every trailer must be secured against movement before a lift truck enters it. Provincial regulations require mobile equipment and vehicles to be secured against inadvertent movement, and CSA B335 and good practice call for wheel chocks or vehicle restraints at docks. The main options, from strongest to weakest, are:

• Vehicle restraints mounted at the dock that hook the trailer's rear impact guard (the underride bar) or lock a rear wheel, interlocked with the dock door and leveller and with a light system for the driver and the operator.
• Wheel-based restraints that position a steel barrier in front of a rear tire.
• Wheel chocks placed in front of the rear wheels on both sides, ideally linked to a sensor or a chock holder that shows when they are in place.
• Keys or glad-hand locks that prevent the driver from leaving: the driver hands the keys to the shipper, or a lock is placed on the trailer's air line connector so the brakes cannot release.

Most well-run sites combine a physical restraint with a procedure: the restraint engages, the light outside turns red for the driver, the light inside turns green for the operator, and only then does the door open and the leveller go out. When loading is finished, the sequence runs in reverse.

Uncoupled trailers

A trailer dropped at the dock without its tractor stands on its landing gear at the front. When a heavy lift truck drives to the front of the trailer, the load on the landing gear rises sharply. Worn or partly raised landing gear can collapse, and a trailer with its load concentrated at the rear can tip up at the front. Trailer stands or jacks placed under the front of the trailer prevent both failures. Many sites require stands under every uncoupled trailer before anyone enters it.

Inspecting the trailer

Before the first truck enters, someone should look inside the trailer and check:

• the floor for holes, rot, broken boards, soft spots and loose plates;
• that the trailer is level enough and the leveller lip rests fully on the bed;
• lighting, adding a dock light if the trailer is dark;
• that the load is stable and not leaning against the doors;
• the trailer's rated floor capacity against the truck's axle load.

Dock levellers and dock boards

Dock levellers bridge the gap and height difference between the dock and the trailer bed. Hydraulic, air-powered and mechanical types all have a deck and a hinged lip that extends onto the trailer. Portable dock boards and plates do the same job at docks without levellers. They must be rated for the combined weight of the loaded truck, with an allowance for the impact and frequency of use; must be secured so they cannot slide; and must be inspected regularly for cracks, worn hinges and damaged lips.

The slope across a leveller also matters. When the trailer bed is much higher or lower than the dock, the leveller becomes a steep ramp. Low-clearance trucks such as pallet trucks can ground out, and loads can shift. The grade is the height difference divided by the leveller length.

Dock edges

An open dock door with no trailer is a serious fall hazard for both trucks and people. Doors should be closed when no trailer is present, and many sites add a barrier across the opening, such as a dock barrier arm, a vertical-storing leveller with a barrier, or a net. Dock edges should be marked with high-visibility striping, and operators should never use a dock door as a turning area. Stand-up truck operators are trained that if a truck goes off a dock, they step off the back rather than staying with it, because the stand-up compartment offers little protection in a fall.

Rail cars

Rail sidings bring their own rules. Rail cars must be secured with wheel stops, derails or other positive protection so that they cannot move while being loaded, and the site must coordinate with the railway so that no locomotive couples to or moves cars while work is underway. Many sites use blue flag or blue light protection, a railway practice where a blue signal at the end of the car or track means workers are present and the equipment must not be moved. Bridge plates between the dock and the rail car must be secured against movement and rated for the loaded truck.

Communication and procedures

Dock incidents often come down to two people who each assumed the other knew what was happening. A written dock procedure should set out:

• how trailers are checked in, positioned and secured, and who confirms the restraint is engaged;
• the light or signal system that tells the driver not to move and the operator that it is safe to enter;
• who controls the trailer's release: for example, the shipper removes the restraint and returns the driver's keys only after the last truck has left the trailer and the leveller is stored;
• where drivers wait, and that they may not enter the dock floor or trailer during loading;
• what to do when equipment fails: no loading on manual chocks alone if the procedure requires a restraint, unless an alternative is approved.