Chocking and Blocking Safety
Chocking and blocking prevent accidental or unintended movement of mobile equipment and cargo while workers are loading, unloading, hitching, unhitching, or performing service or maintenance. Chocking the wheels of a truck, trailer, tractor, or other piece of mobile equipment provides a physical stopper to the wheels to prevent runaways that can crush and injure workers. Blocking stabilizes cargo loads to prevent shifting and trailer overturns or provides a physical barrier on equipment to prevent accidental activation during maintenance.
When chocking, use specially designed truck wheel chocks of the appropriate size and material to securely hold the vehicle. Don’t use lumber, cinder blocks, rocks, or other make-shift items to chock. Make it easy to find and use the correct chocking equipment; store chocks inside trailers, truck rigs and/or other mobile equipment. Keep chocks available at loading docks; chain the chocks to the dock to prevent them from being misplaced. 
If you drive a truck, tractor, or other mobile equipment, use special caution when exiting the vehicle. Ensure that the brakes are set, the vehicle is at a complete standstill, and that it will not roll forward or backward before you exit. If you are performing maintenance or parking the vehicle for an extended period of time, chock the wheels. To properly chock a free-standing vehicle, place chocks on the left and right rear axle wheels. It is safest to chock both the front and back wheels on both sides of a vehicle. Some vehicle wheels may also need to be chocked at the front and back of each tire.
Ensure that trailers are firmly placed against the loading dock edges and prevent rollaways by using chocks. Place chocks on the left and right wheels that are closest to the loading dock. This placement allows a forklift to push down on the trailer wheels and seat them more firmly against the chock. If only the front axle is chocked, a forklift could push the trailer forward and loosen the chock or cause the wheel to jump the chock. The driver, dock workers, and forklift drivers share the responsibility to ensure that the truck and trailer wheels are properly chocked.
Use extra caution when driving a forklift into a trailer from the dock edge; if the trailer rolls away from the dock edge, the forklift can fall into the gap and cause severe injuries or death. Never drive a forklift into a trailer until you ensure that the wheels are properly chocked. Ensure that the trailer floor is in good condition and that it can support the weight of the forklift and its load.
Block or secure trailer cargo to prevent the load from shifting during transit and unloading. Shifting loads can strike, injure, and engulf workers while a sudden shift in center of gravity can overturn a trailer. Securely block all cargo, not just wheeled equipment and round items (e.g., wire reels). Block items separately and on all four sides using lumber thick enough to prevent cargo movement. Use nails or spikes long enough to secure the lumber and drive them in at opposing angles. Don’t use other freight or cargo as a block. When performing maintenance on equipment that could pose a pinch hazard, block it to prevent accidental activation.