For operations covered by 49 CFR 392.5, how long before going on duty must a driver avoid alcohol?
Correct answer: At least four hours
Four hours is the minimum interval. Remaining alcohol or impairment still prohibits duty.
Source: 49 CFR 392.5(a)(1) ↗
A driver covered by 49 CFR 392.5 has a measured alcohol concentration below 0.04. Does that alone make on-duty driving permissible?
Correct answer: No; the rule prohibits any measured alcohol concentration on duty
The on-duty prohibition is separate from the 0.04 disqualification threshold.
Source: 49 CFR 392.5(a)(2) ↗
A driver receives an out-of-service order for violating 49 CFR 392.5. What period does this alcohol rule specify?
Correct answer: 24 hours from issuance of the order
The order starts the 24-hour period, and its terms must be obeyed.
Source: 49 CFR 392.5(c) ↗
Which alcohol concentration does Texas DPS identify as a commercial-driving disqualification ground while operating a CMV?
Correct answer: 0.04 or greater
This CMV threshold is not permission to drive with a lower concentration or while impaired.
Source: CDL Disqualification Reinstatement: alcohol concentration while operating a CMV ↗
After drinking, a driver uses strong coffee and a cold shower. What happens to the time needed for the body to eliminate alcohol?
Correct answer: Those measures do not speed alcohol elimination
Feeling more awake is not the same as being sober. The body needs time to process alcohol.
Source: Texas DL-7C March 2026, section 2.22.1: How Alcohol Works, PDF page 67 ↗
Why can a driver who has been drinking be a poor judge of their own fitness to drive?
Correct answer: Alcohol can impair judgment and self-control early
Early impairment can weaken the very judgment needed to recognize the danger.
Source: Texas DL-7C March 2026, section 2.22.1: Alcohol and the Brain, PDF page 68 ↗
Does choosing beer instead of spirits eliminate the risk of alcohol-related driving impairment?
Correct answer: No; beer, wine and spirits can all supply impairing alcohol
The alcohol dose matters. The type or reputation of the drink does not make driving safe.
Source: Texas DL-7C March 2026, section 2.22.1: What Is a Drink?, PDF page 68 ↗
You cannot remember the last few miles and have missed a familiar exit. What should these signs suggest?
Correct answer: Possible fatigue requiring a safe stop and rest
Memory gaps and missed signs are listed fatigue warnings, even without obvious head nodding.
Source: Texas DL-7C March 2026, section 2.11.2: Warning Signs of Fatigue, PDF page 53 ↗
You can choose between equally lawful trip schedules. Which better follows the handbook’s fatigue-prevention guidance?
Correct answer: Driving during hours when you are normally awake
Plan around normal waking hours and adequate rest. A convenient schedule does not remove the need for sleep.
Source: Texas DL-7C March 2026, section 2.11.2: Preventing drowsiness before a trip, PDF page 53 ↗
Why is repeated coffee an unreliable plan for completing a trip without adequate rest?
Correct answer: Its temporary alerting effect wears off and does not replace sleep
The handbook warns against relying on caffeine to prevent fatigue. Rest remains necessary.
Source: Texas DL-7C March 2026, section 2.11.2: Maintaining alertness while driving, PDF page 53 ↗
A cardboard box lies in your lane. Why should you avoid assuming it is safe to drive over?
Correct answer: It may hide heavy or solid contents that damage the vehicle
Recognize debris early and choose a safe response without a sudden uncontrolled maneuver.
Source: Texas DL-7C March 2026, section 2.8.2: Foreign Objects, PDF page 46 ↗
Your truck’s right wheels run near a sharp pavement drop-off beside a sign. What added clearance hazard can develop?
Correct answer: The vehicle can tilt and move its upper body toward the sign
An uneven edge can tilt a tall vehicle toward roadside objects and make steering difficult.
Source: Texas DL-7C March 2026, section 2.8.2: Drop Off, PDF page 46 ↗
