Seeing and Communicating
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Look 12-15 seconds ahead in town and farther on the open road. Check mirrors every 5-8 seconds. Scan for brake lights, cross traffic, pedestrians, and road-surface changes. Keep your eyes moving; a fixed stare hides developing hazards.
Communicate
Signal at least 100 feet before a turn; earlier at highway speed. Use four-way flashers when moving slowly or stopped in a hazardous spot. Use the horn only to warn. Tap the brakes to warn a tailgater, and turn on headlights in rain or gloom so others see you.
Blind spots
Tractor-trailers have large no-zones on both sides, directly behind, and in front. Don't linger alongside another vehicle. Before a lane change: mirror, signal, mirror, blind-spot check, then move.
Worked example
A driver wants to change lanes but sees a car only in the right mirror. Reasoning: one mirror sighting is not enough; the car may be in the blind spot or closing fast. The driver should signal, check the mirror again, turn the head to check the blind spot, and wait if unsure.
Traps
Signaling after the maneuver; using the horn as a substitute for braking; assuming a mirror shows the whole lane; forgetting to cancel a signal after a lane change.