What is the typical stopping distance for a commercial vehicle at 55 mph?

Answer: B — 400 feet

The typical stopping distance for a commercial vehicle traveling at 55 mph is approximately 400 feet. This distance accounts for the reaction time of the driver and the braking distance required to bring the heavier commercial vehicle to a stop. When a driver perceives a need to stop, there is a delay in their reaction time—typically around 1.5 seconds. During this time, the vehicle continues to travel forward. Given a speed of 55 mph, that initial reaction distance can be about 121 feet. Once the driver engages the brakes, the vehicle must then cover the distance required to decelerate, which can be affected by the vehicle's weight, brake condition, and road surface. When you combine both the reaction distance and the braking distance, it culminates in the approximate stopping distance of 400 feet for a commercial vehicle at this speed. Understanding this distance is critical for safe driving practices, ensuring drivers maintain adequate space from the vehicle in front and can react promptly to emergencies or road conditions.