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The Safety Brief In our podcasts we give short but valuable overviews
and insights into how contractors and safety managers
can be even more effective in protecting their workers.
In our podcasts we give short but valuable overviews and insights into how contractors and safety managers can be even more effective in protecting their workers.

Are Semi-Trailers Permit-Required Confined Spaces?

Permit-required confined spaces aren’t just sewer pipes. Semi-trailers can be hazardous too. Hear about hazards in three trailer types, empty and loaded.

In this 3½ minute podcast, Dan Clark describes OSHA’s standard on PRCS (permit-required confined spaces) for big-rigs.

Dan also defines confined spaces (CS), and offers tips on CS and PRCS programs for safety managers.


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Dan Clark: When you think of confined spaces in the workplace, a truck probably isn’t the first space that comes to mind. Semi-trailers, though, can be confined spaces in certain situations. In some cases they can even be permit-required confined spaces. We’ll stare down the throat of this not-so-obvious safety issue next.

Hello I’m Dan Clark with The Safety Brief. We go toe-to-toe with health and safety hazards in today’s unpredictable industrial and construction worksites brought to you by

OSHA’s picky about tanks, storage bins, tunnels, sewers, silos, closets and cubbyholes. They’re confined spaces. Semi-trailers can be just as dangerous to workers. They can be considered confined spaces or permit-required confined spaces.

THE OSHA STANDARD. Well, lets see. What’s up with these two designations?


• It’s a space large enough for a person to enter and perform work;
• Has limited or restricted entry and exit; and
• Isn’t meant for continuous occupancy

PERMIT-REQUIRED CONFINED SPACE, or PRCS. Has all of the above, plus:

• A hazard. Examples:

○ A hazardous atmosphere;
○ The chance of material engulfing a worker;
○ Walls or floors that slope inward and could trap someone;
○ Risk of electrocution;
○ Unguarded machinery; and more.

TYPES OF SEMI-TRAILERS AND THEIR RISKS. Let’s look at the three types and how they rank when they’re empty and loaded.

1. Open top semi-trailers.

• When empty, they are confined spaces if there’s no open exit door or other means of getting out of there.
• When carrying a load such, as soil, sand or wood chips they are permit-required confined spaces. The hazard is present. The contents could engulf a person.

2. Semi-trailers with a normal configuration of doors at the back.

• When empty, they are not confined spaces if the doors are secured open. If the doors are closed they are confined spaces.
• When carrying a load, it depends on the contents. If what’s inside presents a hazard in any way, the semi trailer could be considered PRCS.

3. Tank trailers. Let me poke my head in one here.

• When empty, they are confined spaces. Always. At a minimum. Yes, there is a hatch here but it’s no quick means of exit.
• When carrying a load, they could be PRCS if the contents could create a hazard. Hazards include someone being engulfed, a hazardous atmosphere, and more.


Have a confined spaces and permit-required confined spaces program. This should include:

• Identifying and labeling semi-trailers as CS or PRCS;
• Having rules for going into these spaces; and
• Doing confined space training with the workers.

For more detailed info about PRCSs, listen to our podcast titled “Permit-Required Confined Spaces” at It’s linked in the transcript of this episode.

That’s a wrap on this podcast, Are Semi-Trailers Permit-Required Confined Spaces? Come back to stay safe and safety compliant in today’s turbulent world of safety requirements. I’m Dan Clark of The Safety Brief, a presentation of Creative Safety Supply.


Semi-trailers and agents images 2010 by U.S. Customs Border Protection / Donna Burton; Tank trailer 2010 by U.S. Dept. Of Energy

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