Question

Difficulty: MediumSpace Ahead and Following Distance

According to commercial driver space management guidelines, an articulated vehicle measuring 60 feet60\text{ feet} in total length traveling at 48 mph48\text{ mph} on a dry roadway maintains an adequate safety cushion when following a lead car at an interval of 6 seconds6\text{ seconds}.

Answer: Answer

Answer

False
The statement is false because a 60-foot60\text{-foot} vehicle traveling at 48 mph48\text{ mph} requires a minimum following distance of 7 seconds7\text{ seconds} (6 seconds6\text{ seconds} for length plus 1 second1\text{ second} for exceeding 40 mph40\text{ mph}), meaning 6 seconds6\text{ seconds} is insufficient.

Step-by-Step Solution

1
Calculate the base following distance based on vehicle length.
60 feet÷10 feet/second=6 seconds60\text{ feet} \div 10\text{ feet/second} = 6\text{ seconds}
The baseline CDL rule requires at least 1 second1\text{ second} for each 10 feet10\text{ feet} of vehicle length.
2
Check the operating speed against the 40 mph40\text{ mph} adjustment threshold.
48 mph≥40 mph48\text{ mph} \ge 40\text{ mph}
Speeds of 40 mph40\text{ mph} and higher require an additional time buffer due to longer braking distances.
3
Add the high-speed safety adjustment to determine the total required following distance.
6 seconds+1 second=7 seconds6\text{ seconds} + 1\text{ second} = 7\text{ seconds}
Adding the 1 additional second1\text{ additional second} yields the minimum safe following interval of 7 seconds7\text{ seconds}, which is greater than the 6 seconds6\text{ seconds} stated.

Key Concept

CDL Following Distance Rule: 1 second per 10 feet of vehicle length under 40 mph, plus 1 additional second for speeds at or above 40 mph.
Estimated Time:1m 0s
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