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Difficulty: MediumSpace Ahead and Following Distance

According to commercial driving safety standards, the minimum required following distance for a 50-foot50\text{-foot} vehicle traveling at 55 mph55\text{ mph} under ideal road and weather conditions is 5 seconds5\text{ seconds}.

Answer: Answer

Answer

False. The minimum required following distance for a 50-foot50\text{-foot} vehicle traveling at 55 mph55\text{ mph} is 6 seconds6\text{ seconds}, not 5 seconds5\text{ seconds}.
The statement is false because operating at 55 mph55\text{ mph} requires adding an extra 1 second1\text{ second} buffer to the baseline 1 second1\text{ second} per 10 feet10\text{ feet} rule, making the required minimum following distance 6 seconds6\text{ seconds} (5+1=65 + 1 = 6).

Step-by-Step Solution

1
Calculate the baseline following distance based on vehicle length.
50 feet/10 feet per second=5 seconds50\text{ feet} / 10\text{ feet per second} = 5\text{ seconds}
The standard CDL formula requires 1 second of following space for each 10 feet of total vehicle length.
2
Evaluate operating speed and apply speed-based adjustments.
Since 55 mph≥40 mph55\text{ mph} \geq 40\text{ mph}, add an extra 1 second1\text{ second}.
At speeds of 40 mph or higher, an additional second is mandatory to compensate for increased stopping and braking distances.
3
Compute total required following interval.
5 seconds+1 second=6 seconds5\text{ seconds} + 1\text{ second} = 6\text{ seconds}
Combine the baseline vehicle length allowance with the high-speed safety increment.

Key Concept

CDL Following Distance Formula and Speed Adjustment
Estimated Time:1m 0s
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Topics

Space Ahead and Following Distance

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