Hours of Service and Fatigue
What the exam tests
Hours of Service and Fatigue tests the driving limits, on-duty window, break requirement, and the effect of fatigue on CMV operation.
Core rules
- Property-carrying drivers generally have an 11-hour driving limit and a 14-hour on-duty window.
- A 30-minute break is required after 8 cumulative hours of driving without at least 30 minutes of non-driving time.
- The 60/7 and 70/8 limits cap on-duty time over 7 or 8 consecutive days.
- A 34-hour restart can reset the cycle when the rules allow it.
- Use an ELD or paper log as required and record duty status accurately.
Worked example
A driver starts at 6 a.m., drives 4 hours, waits 2 hours, then drives 5 hours. Total driving is 9 hours, within the 11-hour limit. The 14-hour window still controls: if the driver reaches 8 p.m. without enough off-duty time, no more driving is allowed even though 2 driving hours remain.
Traps that cost marks
Counting only driving time, forgetting the 30-minute break, assuming off-duty time resets the 14-hour window, and falsifying logs. Fatigue is a hazard even when the numbers are legal.
Key idea
The 14-hour window can end driving before the 11-hour driving limit does.