General Knowledge · Alcohol, Other Drugs, and Driving
How long before going on duty or operating a commercial motor vehicle must a driver avoid using alcohol or being under its influence?
1.4 hours before going on duty or operating the vehicleCorrect answer
2.24 hours before going on duty or operating it
3.No window at all; the ban begins only at the wheel
4.1 hour before going on duty or operating it
Explanation
A driver may not use alcohol or be under its influence within 4 hours before going on duty or operating a commercial motor vehicle, under 49 CFR 392.5. The wrong options each pick a different, incorrect window, or deny that any pre-duty window exists at all, when the regulation specifically sets this rule apart from, and in addition to, the separate on-duty prohibition that governs zero-tolerance while actually on duty.
Source: 49 CFR 392.5
Related Alcohol, Other Drugs, and Driving questions
- What is the federal rule on alcohol use while a driver is on duty, operating, or in physical control of a commercial motor vehicle, separate from the 4-hour pre-duty rule?
- Which of the following is prohibited for a driver who is on duty, under 49 CFR 392.4?
- When does the federal drug prohibition NOT apply to a driver taking medication?
- If a driver becomes too ill to drive safely, what is the correct response?