Wheel Chocks
How to Use Wheel Chocks: OSHA Slope & Incline Rules
Cojo
May 7, 2026
7 min read
Wheel chocks must be placed against the tire (not in front of it), engaged after the parking brake is set (not before), and used in pairs on flat ground or singly on the downhill side on a slope. The U.S. Occupational Safety and Health Administration governs dock-loading chock use at 29 CFR 1910.178(k), the U.S. Department of Transportation governs commercial motor vehicle chock use at 49 CFR 392.20, and the Federal Aviation Administration covers aviation ramp use at AC 150/5210-25. Improper placement is one of the most common general-industry safety citations.
OSHA's general-industry citation database documents thousands of wheel-chock-related violations per year, and the dominant root cause is improper placement rather than absent chocks. A chock placed in front of the tire instead of against it does nothing; a chock placed before the brake is set rolls out of position the moment the operator releases the brake; a single chock placed on the uphill side of a slope-parked truck cannot prevent downhill roll. Each of these failure modes is preventable.
The U.S. Bureau of Labor Statistics documents preventable rollaway-vehicle fatalities each year. Most are at loading docks, fleet yards, or construction sites where chocks were either absent or placed incorrectly.
The pair-of-chocks rule: on flat ground, place two chocks against one tire -- one in front and one behind. The two chocks lock the tire against forward and rearward roll regardless of which direction the parking brake fails or the load shifts.
OSHA 29 CFR 1910.178(k)(1) names "wheel chocks" in the plural specifically to invoke this rule. Inspectors interpret a single chock at a flat-ground dock position as non-compliance even when the parking brake is set. The pair-of-chocks rule is also the standard FAA guidance for aircraft on flat-ramp parking under AC 150/5210-25.
On a slope the rule changes. A single chock placed on the downhill side of one tire is acceptable provided the chock is sized for the slope angle and vehicle weight. Two chocks on a slope (one upslope, one downslope) is preferred. Single-chock-uphill is wrong; the chock must be on the downhill side because the parking brake is the primary uphill restraint and the chock's job is to back up gravity-direction roll prevention.
The OSHA-compliant dock-chock placement sequence has six steps. The order matters; doing step 4 before step 3 is a common citation finding.
The truck must be fully stopped at the dock with the engine off (or with the engine running only if the driver remains in the cab and the regulation specifically permits). Do not begin chock placement while the truck is still moving.
The parking brake (sometimes called the trolley brake or maxi-brake on Class 8 trucks) must be set first. Visual confirmation: the brake-set indicator light or the hand-valve handle position. The U.S. Department of Transportation 49 CFR 392.20 places the brake-set responsibility on the driver, not the dock operator -- but the dock operator confirms before chocking.
Walk to the rear of the trailer along the front (cab side) rather than between the trailer and the dock. The trailer-to-dock space is the highest-risk pinch point at any dock; never approach a chock placement through that gap.
OSHA 29 CFR 1910.178(k)(1) specifies "rear wheels." The chocks go against the rearmost tires of the trailer (the tandem-axle pair on a typical Class 8 trailer). One chock in front, one chock behind. Place each chock so that its angled face contacts the tire tread along its full width, not just at one edge.
The chock must make full contact with the tire. A chock that sits 1/4 inch off the tire is non-compliant because tire roll within that gap can build momentum before the chock catches. Push the chock firmly against the tire with a gloved hand or with the toe of a steel-toed boot.
Loading-dock operations should not proceed until the dock operator signals "cleared" to the forklift operator inside the trailer. The signal pattern depends on the site -- LED indicator panels, two-way radio, or visual hand signal. The U.S. Occupational Safety and Health Administration's general-duty clause requires a documented procedure for the cleared signal.
Slope chocking changes the procedure in two ways. First, the chock goes only on the downhill side of the tire (or both sides with priority on the downhill placement). Second, chock size must scale with slope angle and vehicle weight.
Slope chocking sizing rule of thumb:
| Slope | Vehicle Class | Recommended Chock Size |
|---|---|---|
| 0 to 3 percent | Class 8 truck | 12-inch heavy-duty rubber |
| 3 to 6 percent | Class 8 truck | 15-inch heavy-duty rubber or urethane |
| 6 to 10 percent | Class 8 truck | 18-inch heavy-duty rubber or urethane, both sides of tire |
| Over 10 percent | Any class | Two chocks per tire on downhill side, plus brake-and-engine-on transmission engagement |
Aircraft chock placement follows similar logic with aviation-specific differences. The FAA's Advisory Circular 150/5210-25 covers aircraft ground-handling equipment.
Standard aircraft chock placement: one chock in front and one behind each main landing gear tire. Wide-body aircraft (B737-class and larger) typically use four chocks per main landing gear -- two on each tire of the dual-tire main gear. Aluminum aviation chocks with rope handles are placed by ground handlers from the front of the aircraft, never from under the wing.
Aircraft on long-term parking, refueling, or maintenance always require chocks regardless of slope or wind. Engine-off on the ramp without chocks is a violation of most operator policies.
Removal is the reverse sequence with one critical addition. Confirm the vehicle is ready to depart -- driver is in the cab, parking brake is still set, and the dock operator has cleared the forklift out of the trailer. Then remove the chocks rear-tire-first, walk back to the cab side along the front of the trailer, and signal "cleared to depart" to the driver.
Common removal-side citations: the dock operator removed chocks while the forklift was still in the trailer (load could shift truck position before brake-and-clutch coordination), or the operator stepped between the trailer and the dock during chock removal.
Cojo's parking-products customers in the Hillsboro and Portland industrial corridors regularly request dock-safety walkthroughs as part of broader site planning. In April 2026 Cojo's lead estimator (NICET Level III, OSHA-30 certified) walked the dock-chock placement sequence above with a Hillsboro distribution warehouse safety committee. The walkthrough caught two procedural drift issues that had developed since the last OSHA audit: chocks were being placed before the driver had set the parking brake (Step 2 sequencing error), and the cleared-signal procedure had become informal rather than documented (general-duty clause exposure). Both items were corrected in the same shift. See our OSHA wheel chock requirements guide for full regulatory citation detail.
Correct wheel chock placement is one of several dock-safety practices that combine to deliver OSHA general-industry compliance. Cojo's site walks include chock-placement procedure review as part of broader parking-products and dock-safety planning. Get a custom quote.
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