Communicating
Communicating is the fifth domain of the Louisiana CDL General Knowledge exam. It tests whether you signal your intentions early and clearly, and whether you use lights, horn, and lane position to tell other drivers what you are doing.
Signals and lights
Signal before turns, lane changes, and stops, and cancel the signal afterward. At night, use headlights; during rain, fog, or snow, use low beams. Use four-way flashers when moving slowly, stopped, or disabled. Tapping the brakes can warn a tailgater that traffic is slowing-but do not brake-check.
Horn and lane position
Use the horn only to warn others, not to express annoyance. A short tap may alert a driver drifting into your lane; a long blast can startle and cause a crash. Lane position also communicates: moving slightly left before a right turn can open clearance, but do not swing wide enough to invite a passing car into the gap.
Worked example
A driver wants to change lanes on a multi-lane highway. The driver signals at least three to five seconds early, checks the mirror, checks the blind spot over the shoulder, and moves smoothly only when the space is clear. The reasoning: the signal gives following and adjacent drivers time to react; the mirror and shoulder check confirm the space is actually open.
Traps
Assuming other drivers see you because you see them, signaling only as you begin the maneuver, forgetting to cancel, and overusing the horn are frequent mark-losers.