What 393.134(b) means in plain language
FMSCR 393.134(b) addresses how large boulders in aggregate loads must be secured during transport. When you're hauling stone or aggregate material, individual large boulders cannot be left loose or inadequately restrained in the cargo area. The regulation requires that these boulders meet specific securement standards to prevent them from shifting, rolling, or falling during transit.
This is a mechanical and operational safety issue. A boulder that breaks free during braking, turning, or highway travel becomes a projectile hazard to your rig, other vehicles, and roadway users. Inspectors look for proper blocking, binding, or containment systems that keep large rocks in place throughout the journey.
If cited, you'll receive a violation notice documenting which boulders or which section of your load failed to meet the standard. This goes into your record immediately and becomes part of your carrier's safety profile.
What our enforcement data actually shows
Across 13 million inspections in our database, 393.134(b) has generated 886 all-time citations. In the last 12 months and last 90 days, we recorded zero citations—indicating this violation is now rare in roadside enforcement. When inspectors do find it, the outcome is severe: our data shows a 100.0% out-of-service rate, meaning every single citation resulted in the vehicle being placed out of service.
For context, the all-FMCSR average out-of-service rate is 31.4%. The 100.0% OOS rate for 393.134(b) reflects how seriously inspectors treat unsecured boulders—a load that fails this standard is considered too dangerous to remain on the road. This code ranks 747th by citation volume among all 3,036 FMCSR codes tracked in our system.
The fact that you see zero citations in recent months suggests either improved compliance in the industry, stricter pre-trip practices among aggregate carriers, or fewer roadside inspections of this particular violation type. Regardless, when it does occur, the enforcement response is immediate and total.
Who gets cited most
Our inspection records show that waste and aggregate service companies dominate the citation history for 393.134(b). Waste Management Inc of Florida (USDOT 856351) leads with 11 citations, followed by Republic Services of Florida LP (USDOT 463595) and Southwest Waste Services LLC (USDOT 3560621), each with 10 citations.
This pattern makes sense: companies that regularly haul stone, aggregate, demolition debris, or quarried material are more likely to encounter large boulders in their loads. The concentration in Florida and Indiana carriers reflects regional geology and aggregate mining activity rather than any systemic compliance gap. Carriers in this sector have strong incentive to invest in proper load securement practices, given the 100% OOS rate.
How severe is this compared to similar codes
Vehicle Maintenance codes in the same category show wide variation in enforcement frequency and severity. For comparison:
- 393.9(a) — Inoperable required lamps has 660,737 citations with a 15.4% OOS rate, making it far more common but significantly less likely to result in immediate out-of-service action.
- 396.3(a)(1) — Inspection/repair/maintenance (general) has 236,919 citations with a 45.3% OOS rate—roughly 267 times more citations than 393.134(b), but still lower OOS frequency than unsecured boulders.
- 393.78 — Windshield condition defective has 157,894 citations with only a 0.3% OOS rate, showing that most maintenance violations are not severe enough to ground a vehicle immediately.
The 100% OOS rate for 393.134(b) is exceptional. It indicates that inspectors view load securement for large boulders as a critical safety failure that cannot be resolved at the roadside—the vehicle must be removed from service until the load is properly secured or reloaded.
How to avoid it
Based on the carrier profiles and vehicle data in our records, here are concrete steps to prevent a 393.134(b) citation:
Before you load:
- Inspect your cargo bed, stakes, and tie-down points. Ensure all binding equipment (chains, straps, binders) is in working order and rated for the load weight.
- Understand the size threshold for your load. Know which pieces qualify as "large boulders" under the regulation and require individual securement.
- Review your carrier's securement standard operating procedure. If you work for an aggregate or waste hauler, this should be documented; follow it exactly.
During loading:
- Position large boulders so they cannot roll or shift laterally. Use blocking materials (wood, stone, or engineered blocks) to prevent movement.
- Verify that tie-down points are secure and that each large boulder is individually restrained if required by the standard.
- Do not rely solely on the weight of the load or adjacent rocks to hold a large boulder in place.
Before departure:
- Walk the entire load bed. Check that no large boulders are loose, partially over the edge, or sitting on unstable surfaces.
- Tug on large rocks to confirm they do not shift when force is applied.
- Inspect all binding equipment visually for damage, rust, or slack before rolling.
During transport:
- Be aware that hard acceleration, emergency braking, or sharp turns will test your load securement. Drive smoothly to reduce stress on the system.
- If you stop for any reason, do a spot check of the load, especially if you've traveled rough terrain or high-speed highway.
The zero citations in the past 90 days suggest that carriers and drivers who handle aggregate loads have gotten this right. Maintain that standard, and you'll stay off the roadside inspection report.