Commercial Driver’s License (CDL) · CDL Manual Chapters
Driver Wellness and Compliance
On this page 6 sections
In 30 seconds
A tired or impaired driver is as dangerous as a truck with bad brakes. The Hours-of-Service rules cap how long a property-carrying driver can drive and work: 11 hours of driving after 10 consecutive hours off, inside a 14-hour window, with a 30-minute break after 8 hours of driving, a 60-hour or 70-hour weekly cap, and a 34-hour restart. Alcohol rules are stricter for CDL holders, with 0.04 percent BAC as the disqualifying line.
Why this matters
The knowledge test asks for the Hours-of-Service numbers and the 0.04 percent BAC rule directly, and on the job those numbers decide whether you are legal to drive each day.
The college version
In normal terms
- Ten hours off first, then no more than 11 hours of driving inside a 14-hour window.
- After 8 hours of driving, take a 30-minute break before driving again.
- Sixty hours in 7 days or 70 hours in 8 days is the weekly ceiling, and 34 hours off resets it.
- At 0.04 percent BAC you are disqualified, and any detectable alcohol puts you out of service for 24 hours.
Concepts in this outline
- Fatigue management — Sleep before trips, watch for drowsiness signs, and stop to rest; caffeine and noise do not replace sleep.
- Hours-of-Service (HOS) — Federal limits on driving and on-duty time for property-carrying drivers, tracked in a log and checked at roadside.
- 11-hour driving limit — After 10 consecutive hours off, you may drive no more than 11 hours.
- 14-hour on-duty window — All driving must happen within 14 hours of coming on duty; breaks do not extend it.
- 30-minute break after 8 hours — After 8 cumulative hours of driving, take at least 30 minutes not driving before continuing.
- 60/70-hour weekly caps — No driving after 60 hours on duty in 7 days or 70 hours in 8 days, depending on the carrier.
- 34-hour restart — Taking 34 or more consecutive hours off resets the weekly count.
- Alcohol/drug prohibitions (0.04% BAC disqualifies CDL holders) — 0.04 percent BAC disqualifies, any detectable alcohol means 24 hours out of service, refusing a test counts as failing.
Eli explains
The same idea, in plain words
Explain it like I’m 10
Fatigue means being too tired to drive well. Think of your body as a phone battery. When it runs low, everything slows down. Tiredness slows your reactions, shrinks your attention, and can put you to sleep. Sleep before a trip. Skip medicines that make you drowsy. Keep the cab cool, and stop when you notice the signs. Yawning, drifting in your lane, and forgetting the last few miles are signals. Coffee and loud music do not recharge you. Only sleep does.
Hours-of-Service (HOS) rules make that advice law for drivers who haul freight. Start with the 11-hour driving limit. After 10 hours off duty in a row, you may drive up to 11 hours. Then you need another 10 hours off. Next is the 14-hour on-duty window. The moment you start work, a clock starts. Fourteen hours later you may not drive, however few of those hours were driving. Inspections, loading, dock waits, and fuel stops all eat the 14 hours. A nap in the middle does not pause the clock. The 14-hour window is the box, and the 11 driving hours fit inside it.
Then comes the 30-minute break after 8 hours. After 8 hours of driving without a 30-minute break, you must take one before driving again. On top of the daily rules sit the 60/70-hour weekly caps. That is 60 hours in any 7 days in a row for a carrier that does not run daily. It is 70 hours in any 8 days for a carrier that does. At the cap, you cannot drive until old hours drop off the count. The 34-hour restart is the full recharge. Take 34 or more hours off in a row and your weekly count resets to zero.
Your log records all this. An inspector can check it at any roadside stop. Faking a log is a serious violation. Your carrier will explain any exceptions.
Alcohol and drug prohibitions are the other half. Blood alcohol concentration, or BAC, is how much alcohol is in your blood. For a CDL holder driving a commercial vehicle, 0.04 percent is the disqualifying level. That is half the 0.08 percent limit for regular drivers. Any alcohol at all puts you out of service for 24 hours. Refusing a required test counts the same as failing one. Driving a commercial vehicle drunk costs your CDL for at least a year the first time. A second conviction means losing it for life. You may not drink or have alcohol on duty, or drive within four hours of drinking. Many medicines are unsafe for driving, so ask a pharmacist first.
Worked example
Jamal Whitfield finishes 10 hours off and comes on duty at 6:00 a.m. for a pre-trip, so his 14-hour window closes at 8:00 p.m. He starts driving at 6:30 and by 2:30 in the afternoon he has 8 hours of driving, so he stops for a 30-minute lunch before he touches the wheel again. He drives 3 more hours, reaching 11 hours of driving at 6:00 p.m., and parks for the night even though his 14-hour window has 2 hours left.
His dispatcher reminds him he is at 66 hours on the 70-hour, 8-day count, so tomorrow he has only 4 hours available unless older days drop off the rolling count, and he plans a 34-hour restart. He has one beer with dinner and does not go near the truck.
Study tools & related lessonsRelated
Educational content only. It is not medical, legal or professional advice. Found an error? Tell us.