Approximately how many feet does a large vehicle traveling at 55 mph require to stop?

Approximately how many feet does a large vehicle traveling at 55 mph require to stop?

• A. About 400 feet
• B. About 100 feet
• C. About 800 feet
• D. About 1200 feet

Answer: (C)

The distance to stop is made up of two parts: the distance you travel while you perceive the hazard and react, plus the actual braking distance once you start braking. At 55 mph, you’re moving about 80 feet per second. If you assume a typical 1.5-second perception–reaction time, that’s roughly 120 feet before you even apply the brakes. For a large vehicle, the braking distance at that speed on dry pavement is around 680–700 feet, since more mass means more distance to slow down. Add those together and you get about 800 feet total to stop. If road conditions are worse (wet, icy, or incline), the stopping distance increases beyond this estimate.

The distance to stop is made up of two parts: the distance you travel while you perceive the hazard and react, plus the actual braking distance once you start braking. At 55 mph, you’re moving about 80 feet per second. If you assume a typical 1.5-second perception–reaction time, that’s roughly 120 feet before you even apply the brakes. For a large vehicle, the braking distance at that speed on dry pavement is around 680–700 feet, since more mass means more distance to slow down. Add those together and you get about 800 feet total to stop. If road conditions are worse (wet, icy, or incline), the stopping distance increases beyond this estimate.