Part 399 — Employee Safety and Health Standards
49 CFR Part 399: Workplace safety standards for employees of motor carriers during vehicle servicing and fueling.
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49 CFR Part 399 establishes employee safety and health standards specifically for motor carrier employees engaged in vehicle servicing, fueling, and maintenance operations. These standards exist alongside — not in place of — OSHA workplace safety requirements, and cover trucking-specific hazards that OSHA’s general industry standards do not fully address.
The primary focus of Part 399 is on the safety procedures for fueling commercial vehicles, inspecting vehicles during maintenance, and working around equipment with significant stored energy (compressed air, hydraulic systems, and electrical systems). The regulation requires that engines be shut off during fueling, that workers not position themselves under improperly supported vehicles, and that proper lockout/tagout procedures be followed during maintenance.
Part 399 is one of the less frequently cited parts of the FMCSRs in roadside enforcement, but it is relevant during FMCSA compliance reviews of carrier operations and during accident investigations involving worker injuries at maintenance facilities. Carriers with in-house maintenance shops should ensure their servicing procedures align with Part 399 in addition to OSHA requirements.
Key Provisions
- Requires engines to be shut off before and during fueling of commercial vehicles.
- Prohibits workers from positioning themselves under vehicles supported only by a floor jack.
- Requires proper vehicle support (jack stands, pit systems) before any under-vehicle work.
- Addresses hazards from compressed air systems, hydraulic systems, and high-voltage electrical systems.
- Applies alongside OSHA requirements — not a substitute for general industry safety compliance.
Why It Matters to Truck Owners
Part 399 matters for any carrier that operates its own maintenance facility or employs mechanics to service its fleet. Worker injuries during vehicle maintenance are covered by both OSHA and Part 399, and FMCSA can cite Part 399 violations during compliance reviews. If you’re buying a carrier operation that includes a maintenance shop, the safety culture and procedures in that shop are part of the compliance picture.
Frequently Asked Questions
Does Part 399 replace OSHA safety requirements for trucking companies?
No — Part 399 applies in addition to OSHA’s general industry safety standards, not instead of them. Motor carrier maintenance facilities must comply with applicable OSHA requirements (29 CFR Part 1910) as well as the trucking-specific standards in Part 399. Where requirements overlap, carriers must meet the more stringent standard.
What are the fueling safety rules under Part 399?
Part 399 requires that the vehicle engine be turned off before and during fueling. The driver or fueling attendant must be in attendance during fueling. Static electricity discharge precautions apply when fueling vehicles with flammable liquids. Smoking within 25 feet of a vehicle being fueled is prohibited.
What does Part 399 require for under-vehicle maintenance?
Before any employee works under a vehicle, Part 399 requires that the vehicle be securely supported by jack stands, pit rails, or a similar device — not just a floor jack. Employees cannot rely on a hydraulic floor jack alone as vehicle support while working underneath. Proper chocking to prevent vehicle roll must also be in place.
Read the official legal text: 49 CFR Part 399 — eCFR.gov (official)
Related Federal Trucking Laws
This page is provided for informational purposes only and is not legal advice. Always verify current requirements at fmcsa.dot.gov or with a qualified transportation attorney.
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