HOS Rules Explained: A Practical Guide to Hours of Service for CDL-A Drivers
If you've been driving for a while, you know that Hours of Service regulations are one of the most misunderstood — and most costly — areas of trucking compliance. Get them wrong and you're looking at fines, out-of-service orders, and points on your CSA score. Get them right and they become second nature, something you barely think about while staying fully legal.
This guide cuts through the legalese and breaks down current FMCSA HOS rules the way experienced drivers actually need to understand them: practically, clearly, and with real examples.
What Are Hours of Service Rules and Why Do They Exist?
The Federal Motor Carrier Safety Administration (FMCSA) established Hours of Service regulations to limit driver fatigue — one of the leading causes of serious truck accidents. HOS rules dictate how long you can drive, how long you must rest, and how your workweek is structured.
They apply to CDL-A drivers operating commercial motor vehicles (CMVs) in interstate commerce. Violating them doesn't just put your safety at risk — it puts your livelihood on the line.
The Core HOS Limits You Need to Know
11-Hour Driving Limit
You may drive a maximum of 11 hours after coming off a 10-consecutive-hour off-duty period. This is your daily driving cap — not negotiable, not extendable under most circumstances.
14-Hour On-Duty Window
Once you begin your shift, you have a 14-hour on-duty window to complete your driving. After that window closes, you cannot drive — even if you haven't used all 11 driving hours. Time spent at a shipper waiting to load? That eats into your 14-hour clock.
This is the rule that surprises newer drivers most. You can't pause the 14-hour clock by going off-duty in the middle of your shift (with one important exception — see the split sleeper berth provision below).
30-Minute Break Requirement
If you've been driving for 8 cumulative hours without a break of at least 30 minutes, you must stop. That break must be spent off-duty or in the sleeper berth — not on-duty/not driving. This rule applies once per shift.
60/70-Hour Weekly Limit
This is your weekly cap:
- 60 hours on-duty in any 7 consecutive days (if your carrier doesn't operate every day of the week)
- 70 hours on-duty in any 8 consecutive days (if your carrier operates every day)
MDX Line operates 7 days a week, so drivers work against the 70-hour/8-day clock. Once you hit that ceiling, you cannot drive until you've shed enough hours.
The Restart and Reset Provisions
34-Hour Restart
If you've burned down your 70-hour clock, you can reset it completely with a 34-consecutive-hour off-duty period. That restart must include two periods between 1:00 a.m. and 5:00 a.m. — a requirement that was reintroduced after being briefly suspended.
After a valid restart, your 70-hour clock resets to zero and you're back to a full week.
10-Hour Off-Duty Reset
At the end of each shift, you need at minimum 10 consecutive hours off duty before driving again. For team drivers or drivers with a sleeper berth, there's more flexibility — see below.
Sleeper Berth Provisions: The Split-Sleeper Option
This is where things get more complex — but also more useful for long-haul OTR drivers.
The split sleeper berth rule allows you to split your required 10-hour off-duty period into two segments:
| Segment | Minimum Time | Counts Against 14-Hour Window? |
|---|---|---|
| Primary sleeper period | 7 hours (must be in sleeper berth) | No — pauses the clock |
| Secondary period | 3 hours (sleeper berth or off-duty) | No — pauses the clock |
Key rules for the split to work:
- Neither segment can be less than the minimums above
- The two segments combined must equal at least 10 hours
- The secondary period (the 3-hour break) does NOT count against your 14-hour window or your 11-hour driving limit
- You need to pair the segments — you can't use two 5-hour sleeper breaks
Used correctly, the split sleeper berth rule gives you meaningful flexibility to push through tough delivery schedules without burning your driving hours.
Adverse Driving Conditions Exception
Encounter unexpected weather, road closures, or traffic that wasn't apparent at the start of your trip? The adverse driving conditions exception allows you to extend your driving window by up to 2 additional hours — giving you 13 hours of driving time in that shift.
This does not extend your 14-hour window, and it requires that the conditions were genuinely unforeseeable. Planned mountain passes in winter don't qualify. An unexpected ice storm that closes a major highway does.
Document the conditions. Your ELD won't automatically apply this exception — you need to annotate your log.
Short-Haul Exception: Do You Even Need an ELD?
If you operate within a 150 air-mile radius of your normal work reporting location and return to that location each shift, you may qualify for the short-haul exception. Under this exemption:
- You don't need to keep a Record of Duty Status (RODS) log
- You don't need an ELD
- But you're still subject to the 11-hour driving limit and the 14-hour on-duty window
Most OTR drivers won't qualify for this, but regional and local CDL-A drivers should understand it.
Common HOS Violations — and How to Avoid Them
| Violation | What Happens | How to Avoid |
|---|---|---|
| Exceeding 11-hour driving limit | Immediate out-of-service order | Monitor your ELD throughout the shift |
| Driving after 14-hour window closes | Heavy fine, CSA points | Plan your on-duty start time carefully |
| Falsifying logs | Loss of CDL, federal penalties | Never edit ELD records improperly |
| Missing the 30-minute break | Fine at roadside inspection | Set a reminder at hour 7.5 of driving |
| Exceeding 70-hour weekly limit | Out-of-service | Track your rolling 8-day total daily |
ELD Compliance: What Your Device Is Actually Recording
Every minute you're behind the wheel of a regulated CMV, your Electronic Logging Device is creating a federal record. ELDs automatically capture:
- Driving time (triggered by vehicle motion)
- On-duty, not driving (you manually log this)
- Off-duty and sleeper berth time
- Engine hours, vehicle miles, and location
Critical ELD habits every driver should build:
- Log in before you move the truck. Motion triggers the driving status automatically — if you're not logged in, that data becomes a compliance nightmare.
- Review your logs at the end of every shift. Errors are far easier to correct in real time than during an inspection.
- Annotate exceptions. If you use the adverse driving conditions exception, document it in your ELD notes immediately.
- Don't let anyone pressure you to falsify records. It is a federal offense. Period.
At MDX Line, drivers use Samsara ELDs — a platform known for its clean interface and reliable syncing. Dispatch can see your HOS status in real time through Centrix AI, which means planners are working with accurate data when they assign loads. That's not surveillance — it's how you avoid getting a 500-mile load dropped on you when you have 3 hours left on your clock.
What Happens During a DOT Inspection
When you're pulled into a weigh station or stopped for a roadside inspection, the officer will typically request:
- Your current day's log
- The previous 7 days of logs (your ELD stores these automatically)
- Driver's license, medical certificate, and registration
HOS violations found during inspection range from warnings to fines exceeding $16,000 for egregious or pattern violations. Out-of-service violations stay on your record for 3 years and affect your employer's CSA score — which is why carriers like MDX Line take HOS compliance seriously in their driver qualification and ongoing monitoring programs.
Staying Sharp: HOS Tips from Experienced OTR Drivers
- Plan your day backward from your delivery appointment. Know what time you need to be there, then figure out when you need to start driving.
- Never burn your sleeper berth time on a truck stop parking lot hunt. That's off-duty time you can't get back.
- Use your 34-hour restart strategically — don't burn it in a truck stop when you could plan it around a weekend at home.
- Talk to your dispatcher before your clock runs out, not after. Experienced dispatchers (like the 24/7 team at MDX Line) can often find a drop yard or secure location near your position when you're running low on hours.
Hours of Service rules aren't designed to make your life harder — they're designed to keep you alive and keep your CDL intact. Understanding them deeply means you make better decisions every day on the road.
At MDX Line, HOS compliance is built into operations from the ground up. Samsara ELDs give drivers a clean, reliable logging platform. Centrix AI helps dispatch plan loads around real-time driver availability. And the 24/7 dispatch team is trained to work with your hours, not against them. If you're looking for a carrier that respects your clock and your career, call us at (888) 249-8984 or visit mdxline.com to learn more about driving for MDX Line.