A safety auditor is calculating the stopping requirements for an air-braked tanker traveling at exactly () under ideal conditions. The auditor determines that the mechanical braking distance (the distance traveled after the brake linings physically engage) is exactly .
Using the standard CDL manual parameters for human perception time, human reaction time, and air brake lag time, what is the total stopping distance of the tanker in feet?
Answer: 303 feet
Answer
303 feet
The total stopping distance for an air-braked vehicle consists of four components: perception distance, reaction distance, brake lag distance, and braking distance. By applying standard CDL parameters, the driver requires 1.75 seconds to perceive the hazard and 0.75 seconds to react, while the air brake system takes an additional 0.5 seconds to actuate. This creates a total pre-braking delay of 3.0 seconds. At a velocity of 66 ft/s, the vehicle travels 198 feet during this delay. Adding this to the 105-foot mechanical braking distance yields a total stopping distance of 303 feet.
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Key Concept
Total Stopping Distance for Air-Braked Commercial Vehicles