In the general stopping-distance formula, which three distances are added together?
Correct answer: A – Perception distance, reaction distance, and braking distance
The general formula is perception distance plus reaction distance plus braking distance. Perception distance is traveled while recognizing the hazard, reaction distance while responding and reaching the brake, and braking distance after the brakes are applied. Air-brake vehicles also have brake-lag distance, which is addressed separately in the air-brake section.
Source: Florida Commercial Driver’s License Manual — §§ 2.6.1 and 5.4.4, “Stopping Distance”


