What is the recommended following distance according to the good rule about bus length and speed?

The recommended following distance for a school bus driver is based on the principle that the driver should allow a greater following distance as speed increases. When considering the length of the bus, the guideline states that for every 10 feet of bus length, the driver should maintain a following distance of one second; this becomes critical for ensuring adequate reaction time to avoid collisions.

For larger and heavier vehicles like a school bus, a one-second following distance for every 10 feet of bus length below 40 mph provides a realistic and safe measure to accommodate the bus's size and stopping distance. This guideline offers drivers the necessary flexibility and safety at higher speeds, particularly because larger vehicles require more time to come to a complete stop compared to smaller vehicles.

Furthermore, the rationale behind using 40 mph as the threshold is that most urban bus routes do not exceed this speed significantly, and maintaining this standard ensures safety in everyday driving conditions. In contrast, the other options suggest shorter following distances based on lower speed limits, which does not account for the increased stopping distance that larger vehicles experience at higher speeds.