49 CFR Part 392: Driving of Commercial Motor Vehicles

49 CFR Part 392 is the rulebook for how a commercial motor vehicle is actually driven. It tells you what conduct is prohibited behind the wheel — driving fatigued, driving after alcohol, texting, carrying a radar detector — what the driver must inspect before and during a trip, and exactly what to do at a railroad crossing, in bad weather, and when the truck ends up stopped on the shoulder.

The part is short compared with Part 393 or Part 395, but it is disproportionately expensive, because most of its sections bind the carrier as well as the driver. The phrase “and a motor carrier shall not require or permit a driver to” appears again and again. When a roadside inspector writes a 392 violation, it lands on the driver’s report and on your company’s safety profile.

What does 49 CFR Part 392 actually require?

Part 392 opens with a rule of precedence. Under 49 CFR 392.2, every CMV “must be operated in accordance with the laws, ordinances, and regulations of the jurisdiction in which it is being operated” — but where an FMCSA regulation “imposes a higher standard of care than that law, ordinance or regulation,” the federal rule wins.

That single sentence is why state traffic convictions show up in your federal safety data. Speeding, running a red light, improper lane change and following too closely are all cited under 392.2 by inspectors, because the driver violated a state law while operating a CMV.

From there the part is organized into eight subparts:

• Subpart A (392.1–392.9b) — general prohibitions: fatigue, drugs, alcohol, schedules, equipment and cargo inspection, operating authority.
• Subpart B (392.10–392.18) — driving rules: railroad crossings, hazardous conditions, seat belts.
• Subpart C (392.20–392.25) — stopped vehicles: hazard flashers, warning devices, flame-producing signals.
• Subpart D (392.30–392.33) — lighted lamps and obscured reflectors.
• Subpart E (392.40–392.41) — license revocation and driver duties.
• Subpart F (392.50–392.52) — fueling precautions.
• Subpart G (392.60–392.71) — prohibited practices, including unauthorized passengers and radar detectors.
• Subpart H (392.80–392.82) — texting and hand-held mobile phones.

What are the fatigue, drug and alcohol rules in Part 392?

Three sections do most of the work here, and all three are written to catch dispatch decisions as well as driver decisions.

Fatigue and illness. 49 CFR 392.3 prohibits operating a CMV “while the driver’s ability or alertness is so impaired, or so likely to become impaired, through fatigue, illness, or any other cause, as to make it unsafe” to begin or continue driving. It applies independently of the hours-of-service clock. A driver can be fully legal on the ELD and still be in violation of 392.3.

Drugs and other substances. 49 CFR 392.4 bars a driver from being on duty while possessing, under the influence of, or using any Schedule I substance, any amphetamine, any narcotic drug or derivative, or any other substance to a degree that renders the driver incapable of safely operating the vehicle. The exception in 392.4(c) covers a substance administered by or under the instructions of a licensed medical practitioner who has advised the driver it will not affect safe operation.

Alcohol. 49 CFR 392.5 prohibits alcohol use, being under the influence, or possession within 4 hours before going on duty or operating a CMV, and while on duty or in physical control of one. A driver found in violation is placed out of service immediately for 24 hours. That driver must report the out-of-service order to the employer within 24 hours and to a State official in the licensing State within 30 days, and may petition for review within 10 days of the order.

Note that 392.5 and Part 382 are separate obligations. The 4-hour rule is a driving prohibition; the testing program is a carrier program.

Schedules. 49 CFR 392.6 prohibits a carrier from scheduling a run that would require the vehicle to be operated at speeds greater than the posted limits. This is the rule behind “the dispatch itself was the violation.”

What must a driver inspect before and during a trip?

Part 392 imposes three inspection duties that sit alongside the systematic maintenance obligations in Part 396.

Equipment. 49 CFR 392.7 requires the driver to be satisfied that the service brakes including trailer brake connections, parking brake, steering mechanism, lighting devices and reflectors, tires, horn, windshield wiper or wipers, rear-vision mirror or mirrors, coupling devices, wheels and rims, and emergency equipment are in good working order. A separate list in 392.7(b) applies to intermodal equipment before it is driven.

Emergency equipment. 49 CFR 392.8 prohibits driving unless the driver is satisfied that the emergency equipment required by 49 CFR 393.95 is in place and ready for use.

Cargo. 49 CFR 392.9 requires that cargo be properly distributed and adequately secured per 49 CFR 393.100 through 393.136, that tailgates, doors, tarpaulins and fastenings are secured, and that nothing obscures the driver’s view or interferes with free movement of the arms or legs. Drivers of trucks and truck tractors must also inspect within the first 50 miles and re-examine the load at set intervals.

What are the Part 392 numbers you have to know?

Requirement	The number	Citation
Alcohol use, influence or possession before duty	Prohibited within 4 hours before going on duty or operating	49 CFR 392.5(a)
Out-of-service period after an alcohol violation	24 hours, immediately	49 CFR 392.5(c)
Reporting that OOS order to the employer	Within 24 hours	49 CFR 392.5
Reporting that OOS order to the licensing State	Within 30 days	49 CFR 392.5
Petition for review of the OOS order	Within 10 days of issuance	49 CFR 392.5
First cargo securement check after departure	Within the first 50 miles	49 CFR 392.9(b)
Cargo re-examination interval	Every duty-status change, or 3 hours, or 150 miles — whichever comes first	49 CFR 392.9(b)
Required stop at a railroad crossing (listed vehicles)	Within 50 feet of, and not closer than 15 feet to, the nearest rail	49 CFR 392.10(a)
Warning devices after stopping on the traveled way or shoulder	As soon as possible, in any event within 10 minutes	49 CFR 392.22(b)
Standard warning device placement	About 10 feet on the traffic side, about 100 feet ahead, about 100 feet behind	49 CFR 392.22(b)
Placement on a divided or one-way highway	200 feet and 100 feet toward approaching traffic, plus one within 10 feet of the rear	49 CFR 392.22(b)
Business or residential district exception	Devices not required if lighting makes the vehicle clearly discernible at 500 feet	49 CFR 392.22(b)
Administrative review after an operating-authority OOS order	Not later than 10 days after issuance	49 CFR 392.9a(c)

What do the railroad grade crossing rules require?

Two sections split the fleet in half.

Under 49 CFR 392.10, a defined group of vehicles must come to a full stop at every grade crossing: every bus transporting passengers, any CMV carrying Division 2.3 chlorine, vehicles carrying hazardous materials that require the placards listed in the rule, and cargo tank motor vehicles used for hazardous materials — loaded or empty. The stop must be made within 50 feet of, and not closer than 15 feet to, the tracks, and the driver must look and listen in both directions before proceeding. Shifting gears while crossing is prohibited.

392.10(b) lists the crossings where no stop is required: streetcar crossings and industrial switching tracks in a business district, crossings where a police officer or flagman directs traffic through, a functioning green traffic control signal, an abandoned crossing marked as such, and industrial or spur line crossings marked “Exempt” by the appropriate authority.

Every other CMV falls under 49 CFR 392.11, which requires approaching at a speed that permits stopping before the nearest rail, and prohibits crossing “until due caution has been taken to ascertain that the course is clear.”

What do you do when the truck is stopped on the shoulder?

This is the sequence inspectors and plaintiffs’ lawyers both reconstruct after a crash, and 49 CFR 392.22 spells it out.

The driver must immediately activate the hazard warning signal flashers whenever the vehicle is stopped on the traveled portion or the shoulder for any cause other than a necessary traffic stop. Then, as soon as possible but within 10 minutes, the driver places the warning devices required by 49 CFR 393.95 — three bidirectional reflective triangles, or the fusee/liquid-burning flare alternatives that section allows.

Placement changes with the road. On a two-lane undivided highway, one device goes roughly 10 feet from the vehicle on the traffic side, one about 100 feet behind in the center of the lane, and one about 100 feet ahead. On a divided or one-way highway, devices go 200 feet and 100 feet toward approaching traffic, plus one within 10 feet of the rear of the vehicle. If the stop is within 500 feet of a curve, crest or other obstruction, the rearward device moves back to between 100 and 500 feet so approaching traffic gets warning.

Two related prohibitions: 49 CFR 392.24 bans attaching a lighted fusee or other flame-producing signal to any part of a CMV, and 49 CFR 392.25 bans flame-producing signals altogether around Division 1.1, 1.2 or 1.3 explosives, loaded or empty Class 3 or Division 2.1 cargo tanks, and any vehicle using compressed gas as motor fuel.

What are the texting and hand-held phone rules?

49 CFR 392.80 prohibits texting while driving and prohibits a carrier from allowing or requiring it. 49 CFR 392.82 prohibits using a hand-held mobile telephone while driving a CMV, with the same carrier-side prohibition. “Driving” in both sections includes being temporarily stationary because of traffic, a traffic control device or other momentary delays — it stops only when the driver has moved to the side of or off the highway and halted somewhere the vehicle can safely remain stationary.

The definitions that matter live in 49 CFR 390.5. Texting is “manually entering alphanumeric text into, or reading text from, an electronic device,” and electronic device expressly includes phones, PDAs, pagers and computers. Use a hand-held mobile telephone means using at least one hand to hold a phone for a voice call, dialing or answering by pressing more than a single button, or reaching for the phone in a way that takes the driver out of the seated driving position restrained by a seat belt.

Both sections carry a narrow exception: contact with law enforcement officials or other emergency services is permitted.

What do inspectors actually check under Part 392?

At roadside, Part 392 is verified mostly by observation and by paperwork the driver is already holding.

• The seat belt, before the truck even stops moving. 49 CFR 392.16 is one of the easiest violations for an officer to observe and one of the most frequently written.
• The dash and cab for a radar detector (392.71), a phone in a cradle mid-call (392.82), or a screen showing an active text thread (392.80).
• Load securement, physically — straps, chains, tarps, and whether the driver can articulate when they last re-checked the load under 392.9.
• Emergency equipment, opened and counted against 393.95, which is how a 392.8 violation is written.
• Operating authority, checked against the MC number and scope. Operating without required authority or beyond its scope under 49 CFR 392.9a results in the carrier being ordered out of service.
• State traffic convictions on the driver’s record, cited under 392.2.

In a compliance review or new-entrant safety audit, the auditor works backward from your dispatch records instead. They are looking for evidence that the carrier required or permitted something: a run scheduled too tight to make legally (392.6), a driver dispatched after reporting illness (392.3), a phone log that shows dispatch calling a driver known to be rolling. Fleets that keep dispatch, hours and driver-communication records in one place — the reason many carriers move this onto a platform like Fleetive — can answer those questions in minutes instead of reconstructing them from texts.

What are the most common Part 392 violations?

Part 392 violations cluster in a handful of predictable places:

1. State law violations cited under 392.2 — speeding, failure to obey a traffic control device, improper lane change, following too closely. In FMCSA roadside data these are consistently among the highest-volume driver violations.
2. Seat belt, 392.16. Purely observational, and it feeds the Unsafe Driving BASIC.
3. Load securement, 392.9. Written together with a substantive Part 393 securement violation more often than not.
4. Emergency equipment, 392.8. Usually a missing or expired fire extinguisher, or fewer than three triangles.
5. Hand-held phone and texting, 392.82 and 392.80. These are disqualifying offenses on a repeat basis under Part 383 and carry driver disqualification exposure, not just points.
6. Railroad crossing violations, 392.10 and 392.11. Low volume, high severity — and a crossing violation is a serious offense under the CDL disqualification rules.
7. Operating beyond authority, 392.9a. An immediate out-of-service order for the carrier, which is why authority scope needs checking before a load is booked, not after.

How do you build Part 392 into daily operations?

Part 392 is behavioral, so it is controlled by policy, training and evidence rather than by a piece of equipment.

Write the prohibitions into the driver handbook in the same “driver may not / company may not require” structure the regulation uses, and get a signed acknowledgment into the driver qualification file described in Part 391. Train specifically on the shoulder-stop sequence and the crossing rules — these are the two places where a driver’s improvised judgment produces both a violation and a catastrophic loss. Review your dispatch practice against 392.6 and 392.3: if a lane cannot be run legally, the schedule is the violation, and no amount of driver coaching fixes it.

Then monitor. Pull your roadside inspection results monthly, sort Part 392 violations by section, and coach the top two. Carriers that track violation history, driver files and equipment records together — the workflow behind fleet compliance tracking — catch the repeat 392.16 or 392.82 driver before it becomes a pattern in the Safety Measurement System.

For the broader picture of how Part 392 sits alongside the rest of the safety regulations, see our FMCSA regulations guide and the DOT compliance guide, or browse the full 49 CFR reference library.

This page is a plain-English summary of 49 CFR Part 392 and is not legal advice. Always read the current regulation text and consult qualified counsel for your specific operation.