Fatigue
Fatigue is the eleventh domain of the Louisiana CDL General Knowledge exam. It tests whether you recognize when you are too tired to drive safely, understand the causes of driver fatigue, and know that rest-not caffeine or a cold blast of air-is the only real remedy.
Causes and signs
Fatigue comes from too little sleep, long driving hours, night driving, and disrupted circadian rhythms. Warning signs include yawning, heavy eyes, drifting in the lane, missing signs or exits, tailgating without meaning to, and not remembering the last few miles. Microsleeps can last several seconds at highway speed-enough to travel the length of a football field.
Prevention
Get adequate sleep before a trip, take scheduled breaks, and avoid driving during the hours when you would normally sleep. Share driving if possible. If you feel sleepy, stop in a safe place and take a nap; caffeine is a short-term aid, not a substitute for sleep.
Hours of service
Federal rules for interstate drivers include an 11-hour driving limit, a 14-hour on-duty window, a 30-minute break after 8 hours without at least 30 minutes of non-driving time, and 60/70-hour limits over 7/8 days. Louisiana intrastate rules may differ, so know which rules apply to your operation.
Worked example
A driver at 3 a.m. drifts onto the shoulder and cannot recall the last exit. The correct response is to stop at a safe location and rest. The reasoning: the driver has already experienced a microsleep; continuing risks a crash, and rolling down the window will not restore alertness.
Traps
Relying on energy drinks, loud music, or chewing gum, and pressing on to “just make the next town,” are frequent mark-losers.