What 393.134B2 means in plain language
FMCSR 393.134B2 addresses the securement of large boulders when they are loaded as cargo on your vehicle. The regulation requires that aggregate large boulders be secured according to specific Department of Transportation rules designed to prevent shifting, falling, or loss of load during transport.
This code is narrowly focused: it applies when your cargo consists of large boulders—not general aggregate, not small rocks, but specifically large boulder-sized material that must meet particular tie-down and containment standards. If you're hauling this type of load, DOT inspectors will verify that your securement devices, blocking, bracing, or containment structures meet the rules outlined in Part 393 of the FMCSR.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.134B2 is extremely rare. We have recorded 2 all-time citations for this code. In the last 12 months, there has been 1 citation, and in the last 90 days, 1 citation. This places 393.134B2 at rank #2651 out of 3,036 FMCSR codes by citation volume.
What makes this citation notable is its out-of-service rate: 100.0%. When cited, both instances in our database resulted in an out-of-service placement. This is substantially higher than the all-FMCSR average OOS rate of 31.4%. That means inspectors are treating cargo securement violations involving large boulders as critical safety defects requiring immediate correction before the vehicle can return to service.
The citation trend shows 1 occurrence in March 2026, indicating this remains an infrequent but serious enforcement area.
Who gets cited most
Our inspection records show that Illinois accounts for the citation activity in our recent data, with 1 citation logged in the last 180 days. That citation resulted in an out-of-service placement, consistent with the 100.0% OOS rate for this code.
By carrier, our data shows fleets such as Anthony Bailes Inc (USDOT 607753) and Ensure Trucking Inc (USDOT 2290774) with 1 citation each in our all-time records. This does not indicate a pattern—it reflects the rarity of this violation across the industry.
How severe is this compared to similar codes
To understand where 393.134B2 sits in the enforcement landscape, we can compare it to other vehicle maintenance codes in the same category.
393.9(a) — Inoperable required lamps shows 660,737 citations and a 15.4% OOS rate. This is far more common than 393.134B2 and results in out-of-service placement much less frequently.
396.3(a)(1) — Inspection/repair/maintenance (general) has 236,919 citations with a 45.3% OOS rate. While still much more frequent than boulder securement citations, this code results in OOS placement less often than 393.134B2's 100.0% rate.
393.47E — Slack adjuster defective accounts for 180,363 citations but carries a 0.0% OOS rate, meaning brake-related defects in that category are typically corrected without removal from service.
The 100.0% OOS rate for 393.134B2 reflects that cargo securement failures involving large boulders are treated as immediate safety hazards, not correctable defects that can be fixed roadside.
How to avoid it
Because 393.134B2 citations are rare, they typically occur when drivers are hauling large boulder aggregate loads—a specialized cargo type. If you transport this material, take these concrete steps:
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Verify your securement devices before loading. Check that all tie-down equipment (straps, chains, binders) is rated for the weight and size of large boulders you'll be carrying. Inspect for cuts, fraying, corrosion, or damage that could fail under road vibration.
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Confirm blocking and bracing placement during pre-trip. Walk the load and verify that blocking or bracing materials are positioned to prevent boulder movement in all directions—forward, backward, and side-to-side. Large boulders shift unpredictably, so redundancy matters.
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Inspect your vehicle's brake and lighting systems. Our data shows that 393.47A (brake chamber defects) and 393.9T (inoperable tail lamp) co-occurred with boulder securement citations in the same inspections. A brake chamber crack or failed tail lamp often triggers a full vehicle inspection, including your cargo securement, so catch these issues during pre-trip.
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Know the aggregate type you're hauling. Large boulders have different securement requirements than crushed stone or gravel. If you're uncertain whether your load qualifies as "large boulders" under the regulation, ask your dispatcher or safety manager before rolling.
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Document your securement setup. Take photos of how your load is secured, especially if you're new to this cargo type. If cited, you'll have evidence that you followed proper procedures, and your fleet can use the photos to coach other drivers.
The 100.0% OOS rate means there is no flexibility: if an inspector finds your large boulders not secured to spec, your vehicle comes out of service. Prevention is far simpler than dealing with a roadside shutdown.