Final answer:
The carrier identification number on a bus must be legible from at least 50 feet during daylight hours to meet safety regulations.
Step-by-step explanation:
The carrier identification number displayed on both sides of the bus must be readily legible from a distance of 50 feet during daylight hours. This requirement is enforced to ensure that identification numbers are visible to inspectors, other drivers, and emergency responders, adhering to safety regulations. For example, a one-hour one-way route operating on a 15-minute schedule requiring 4 buses in service in each direction signifies the importance of clear vehicle identification for efficient operation and coordination.