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Difficulty: HardSpace Ahead and Following Distance

When operating a 70-foot combination vehicle at a speed of 55 mph on a dry, level highway, maintaining a 7-second time gap behind the preceding vehicle satisfies the minimum recommended following distance under commercial driver safety guidelines.

Answer: Answer

Answer

False
Under CDL space management guidelines, calculating following distance requires 1 second per 10 feet of vehicle length plus 1 additional second when traveling at 40 mph or faster. A 70-foot vehicle traveling at 55 mph requires 7+1=8 seconds7 + 1 = 8\text{ seconds} of following distance; maintaining only 7 seconds fails to provide the required safety cushion.

Step-by-Step Solution

1
Calculate the baseline time interval based on total vehicle length.
70 ft÷10 ft/sec=7 seconds70\text{ ft} \div 10\text{ ft/sec} = 7\text{ seconds}
Commercial vehicle following distance standards establish a baseline requirement of 1 second for every 10 feet of vehicle length.
2
Evaluate the vehicle speed and apply the speed modifier.
Since 55 mph≥40 mph55\text{ mph} \ge 40\text{ mph}, add 1 second1\text{ second}.
For operating speeds at or above 40 mph, commercial driving guidelines require adding 1 additional second to the baseline following distance to account for increased stopping distance.
3
Compute the total required following distance.
7 seconds+1 second=8 seconds7\text{ seconds} + 1\text{ second} = 8\text{ seconds}
Total minimum safe following distance equals the vehicle length baseline plus the speed adjustment buffer.
4
Compare the calculated requirement against the 7-second time gap stated in the scenario.
7 seconds is less than the required 8 seconds.
Because the maintained buffer (7 seconds7\text{ seconds}) is less than the minimum safe standard (8 seconds8\text{ seconds}), the claim is false.

Key Concept

CDL Following Distance Formula and High-Speed Adjustments
Estimated Time:1m 30s
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Topics

Space Ahead and Following Distance

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