Under ideal driving conditions, a commercial driver operating a 30-foot straight truck at … — Commercial Driver's License (CDL) General Knowledge Exam

Under ideal driving conditions, a commercial driver operating a $30$ -foot straight truck at a speed of $35\text{ mph}$ must maintain a minimum following distance of at least $3\text{ seconds}$ behind the vehicle ahead.

Answer: Answer

Answer

True

The statement is true because the CDL standard formula mandates

1\text{ second}

for each

10\text{ feet}

of vehicle length when driving under

40\text{ mph}

. Dividing

30\text{ feet}

10

yields exactly

3\text{ seconds}

of required following distance under ideal conditions.

Step-by-Step Solution

Identify the vehicle length and cruising speed from the scenario.

The truck length is

30\text{ feet}

and the operating speed is

35\text{ mph}

These values are needed to apply the CDL following distance formula.

Calculate the base following distance using the standard rate of

1\text{ second}

per

10\text{ feet}

of vehicle length.

\frac{30\text{ ft}}{10\text{ ft/sec}} = 3\text{ seconds}

Commercial motor vehicles require

1\text{ second}

of following buffer for each

10\text{ feet}

of overall vehicle length.

Determine if the speed modifier applies.

The speed is

35\text{ mph}

, which is below

40\text{ mph}

, so no additional second is added.

The additional

1\text{ second}

speed modifier only applies at speeds of

40\text{ mph}

and above.

Key Concept

CDL space ahead formula below 40 mph (1 second per 10 feet of vehicle length)

Estimated Time:45s

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