You are driving a 40-foot bus at 50 mph on a dry road with good visibility. What minimum following interval should you maintain?
Correct answer: A – 5 seconds
A 40-foot vehicle requires four seconds under the manual’s one-second-per-10-feet guideline. Because the bus is traveling faster than 40 mph, add one more second, producing a five-second interval. The Montana CDL manual also advises leaving substantially more space when the roadway is slippery.
Source: Montana Commercial Driver License Manual — § 2.7.1, “Space Ahead”

