Under the standard commercial driver space cushion rule, an operator driving a 40\text{-fo… — Commercial Driver's License (CDL) General Knowledge Exam

Under the standard commercial driver space cushion rule, an operator driving a $40\text{-foot}$ flatbed truck at a steady cruising speed of $42\text{ mph}$ on a dry highway requires a minimum following distance of $4\text{ seconds}$ .

Answer: Answer

Answer

False

The correct evaluation is false because the standard CDL following distance formula prescribes

1\text{ second}

per

10\text{ feet}

of vehicle length plus

1\text{ additional second}

for speeds at or above

40\text{ mph}

. For a

40\text{-foot}

vehicle traveling at

42\text{ mph}

, the required minimum following distance is

5\text{ seconds}

, not

4\text{ seconds}

Step-by-Step Solution

Calculate the base following distance required for the vehicle length

40\text{-foot}

vehicle requires

4\text{ seconds}

based on the standard rule of

1\text{ second}

per

10\text{ feet}

of vehicle length (

40 \div 10 = 4

Vehicle length establishes the baseline time gap needed to maintain an adequate safety cushion.

Evaluate the cruising speed and apply any required speed adjustments

The truck is traveling at

42\text{ mph}

, which is at or above

40\text{ mph}

, requiring an additional

1\text{ second}

(

4\text{ seconds} + 1\text{ second} = 5\text{ seconds}

Speeds of

40\text{ mph}

and higher require greater stopping distances, necessitating an extra second of space cushion.

Compare the calculated requirement to the statement

The statement asserts that

4\text{ seconds}

is required, whereas the actual minimum requirement is

5\text{ seconds}

Omitting the speed adjustment leaves an insufficient following distance under CDL safety standards.

Key Concept

CDL Space Ahead Formula (Length and Speed Adjustments)

Estimated Time:1m 0s

Question

Answer

Step-by-Step Solution

Key Concept

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