Hours of Service and Fatigue
This domain tests hours-of-service limits, logging, and fatigue recognition. The exam asks you to calculate remaining drive time and identify when rest is required.
Limits
For interstate operations: 11 hours driving after 10 consecutive hours off duty; a 14-hour on-duty window; a 30-minute break after 8 cumulative hours of driving; and 60 hours in 7 days or 70 hours in 8 days. Sleeper-berth splits may be 8/2 or 7/3. Most interstate drivers use an ELD to record duty status.
Fatigue
Warning signs include yawning, heavy eyes, drifting, and missing exits. Stop and rest; caffeine is not a substitute for sleep.
Worked example
A driver has been on duty 13 hours and driving 10 hours, with a 30-minute break after the sixth driving hour. Reasoning: the 11-hour driving limit leaves 1 hour, but the 14-hour window leaves only 1 hour too, so the driver may drive 1 more hour and must then stop.
Traps that cost marks
Confusing driving time with on-duty time; counting the 14-hour window as driving only; forgetting the 30-minute break; assuming a split sleeper period always resets the 14-hour clock.