Which of the following is NOT a component of the total stopping distance for air-brake vehicles?

• A. Slope of grade
• B. Perception distance
• C. Reaction distance
• D. Brake Lag Distance

Answer: (A)

The total stopping distance for air-brake vehicles is built from four elements that cover the whole process from spotting a hazard to coming to a stop: perception distance, the distance you travel while you recognize the hazard; reaction distance, the distance you cover while you decide to act and begin braking; brake lag distance, the delay between pressing the brake and the brakes actually engaging in an air-brake system; and braking distance, the distance required to stop once the brakes are applying. The slope of grade isn’t listed as a separate component of this total. It can influence how far you need to stop on a hill, but that effect is absorbed into braking distance rather than being a distinct component in the standard breakdown.