A commercial driver is operating a 60\text{-foot} combination vehicle along an urban arter… — Commercial Driver's License (CDL) General Knowledge Exam

A commercial driver is operating a $60\text{-foot}$ combination vehicle along an urban arterial road at a steady speed of $35\text{ mph}$ . According to standard commercial vehicle safety guidelines, what is the minimum safe following distance the driver should maintain behind the vehicle ahead?

A
$3\text{ seconds}$
B
$5\text{ seconds}$
$6\text{ seconds}$ Answer
D
$7\text{ seconds}$

Answer

6\text{ seconds}

For commercial vehicles, the standard formula specifies

1\text{ second}

for every

10\text{ feet}

of vehicle length when traveling under

40\text{ mph}

. For a

60\text{-foot}

vehicle traveling at

35\text{ mph}

, the required following distance is exactly

\frac{60}{10} = 6\text{ seconds}

. Because the vehicle is moving below

40\text{ mph}

, no extra second is added.

Step-by-Step Solution

Determine base following distance from vehicle length

\frac{60\text{ ft}}{10\text{ ft/sec}} = 6\text{ seconds}

Commercial vehicle guidelines mandate at least

1\text{ second}

of following distance for each

10\text{ feet}

of vehicle length.

Evaluate operating speed against the speed threshold

The travel speed is

35\text{ mph}

, which is below the

40\text{ mph}

threshold.

The additional

1\text{ second}

penalty only applies when traveling at or above

40\text{ mph}

Calculate total minimum following distance

6\text{ seconds} + 0\text{ seconds} = 6\text{ seconds}

No extra second is added, leaving the total required cushion at

6\text{ seconds}

Key Concept

CDL Following Distance Formula: 1 second per 10 feet of vehicle length under 40 mph, plus 1 additional second at 40 mph or above

Estimated Time:1m 0s

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