What primary factor determines the maximum number of pupils a school bus can carry?

The maximum number of pupils a school bus can carry is determined by the manufacturer's rated capacity. This capacity is based on the design and specifications of the bus, which includes considerations for safety, space, and comfort. Manufacturers establish this capacity by evaluating various factors, such as the size of the bus, the number of seats designed, and safety regulations that dictate how many passengers can be safely transported at one time.

Local regulations, driver's discretion, and school district policy may influence operational practices, but they cannot legally change the safety limits set by the manufacturer. The manufacturer's rated capacity ensures that the bus operates within its designed parameters, which helps maintain passenger safety and bus integrity. Therefore, the manufacturer's specifications are the primary factor used to determine passenger capacity.