What 393.136(b) means in plain language
FMCSR 393.136(b) addresses how boulders and similar heavy cargo must be positioned and secured on a commercial vehicle. When you're transporting rocks, aggregates, or similar bulk materials, the way those items sit on your trailer matters—both for structural safety and for preventing load shift during transit.
The regulation requires that boulders be placed and positioned in a manner that keeps the load stable, prevents it from rolling or shifting, and maintains the integrity of your vehicle. Poor positioning can lead to uneven weight distribution, damage to the trailer frame or bed, or dangerous load movement that puts other motorists at risk.
This code falls under vehicle maintenance and equipment standards. An inspector citing this violation is saying that during a roadside inspection, they observed boulders or similar cargo arranged in a way that violates the positioning standard.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.136(b) has been cited only 3 times in our database. There have been zero citations in the last 12 months and zero in the last 90 days, making this one of the rarest violations we track.
Ranked 2551st out of 3,036 FMCSR codes by citation volume, this code is exceptionally uncommon. However, when it is cited, the consequences are severe. Our data shows a 100.0% out-of-service rate for the 3 citations on record—meaning every single citation resulted in the vehicle being placed out of service. This is dramatically higher than the all-FMCSR average out-of-service rate of 31.4%, indicating that inspectors treat this violation as a serious safety defect requiring immediate correction before the vehicle can return to service.
The rarity of citations suggests that most carriers either avoid this violation entirely or correct it before roadside inspection. The extreme OOS rate, by contrast, signals that when inspectors do encounter improper boulder placement, they view it as a critical safety issue.
Who gets cited most
Our inspection records show that boulder placement citations are so rare that geographic and carrier patterns are minimal. The citation data is limited to only 3 all-time cases across the entire dataset. Among carriers with documented citations for this code, our data shows fleets such as Grace Transport Inc (USDOT 611104) with 2 citations and Steel Brought In LLC (USDOT 1547730) with 1 citation, but these numbers reflect a very small sample and do not indicate systemic issues.
Given the rarity of enforcement, this violation is not concentrated in any particular state or region. The enforcement pattern suggests that this code is cited only when inspectors observe a significant, obvious safety defect in cargo positioning.
How severe is this compared to similar codes
Vehicle maintenance and equipment violations span a wide range of severity and frequency. To understand where 393.136(b) sits, compare it to other codes in the same category:
393.9(a) — Inoperable required lamps is cited far more often, with 660,737 all-time citations but a lower 15.4% out-of-service rate. Lamp defects are common and often correctable without immediate vehicle removal.
396.3(a)(1) — Inspection/repair/maintenance (general) has 236,919 citations and a 45.3% out-of-service rate, indicating that general maintenance failures are enforced more frequently but with less consistency in OOS outcomes.
393.47E — Slack adjuster defective appears 180,363 times in our records with a 0.0% out-of-service rate, showing that some maintenance violations are cited as warnings rather than safety-critical defects.
In contrast, 393.136(b)'s 100.0% out-of-service rate places it in a higher-severity category. When this violation is cited, it is treated as a non-negotiable safety issue that grounds the vehicle immediately.
How to avoid it
Because this violation is extremely rare and enforcement data is limited, the most direct prevention strategy is to ensure proper load securement and positioning during pre-trip and loading operations:
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Inspect the load bed or trailer surface before loading. Verify that the bed is clean, level, and free of damage that could cause uneven settling of cargo. A damaged or uneven surface can cause boulders to rest improperly.
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Distribute boulder weight evenly across the trailer or bed. Avoid concentrating large stones or boulders in one area, which can create load imbalance and shift during braking or turning.
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Check for load stability during loading. As boulders are placed, ensure they rest flush against the trailer bed or each other without gaps that could allow movement. Rocks that are tilted or partially suspended are improperly positioned.
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Use appropriate containment if required. Depending on the size and type of boulder cargo, side racks, end gates, or tarping may be required to prevent shift. Ensure all containment equipment is secure and properly positioned.
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Perform a post-load walk-around. Before departing, walk the full length of the load and verify visually that all boulders are stable and positioned flush against the trailer structure.
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Document your pre-trip inspection. If you inspect the load and certify it as properly positioned, you have evidence of due diligence if an inspector stops you.
Given the extreme rarity of this citation (only 3 in our entire database), the most important takeaway is that boulder or aggregate transport is low-risk if you follow standard load-securing practices. Focus on even weight distribution, stable resting positions, and secure containment, and you are unlikely to encounter this violation.