(a) Seating Capacity. Except as provided in subsection (e), the number of passengers (excluding infants in arms) shall not exceed the number of safe and adequate seating spaces, or for school buses, school pupil activity buses, youth buses, and farm labor vehicles, the number of passengers specified by the seating capacity rating set forth in the departmental Vehicle Inspection Approval Certificate.

(b) Weight. No more passengers shall be transported than the number whose weight, in addition to the weight of any property transported, can be carried without exceeding the manufacturer's maximum gross vehicle weight rating or the combined maximum rating of the tires supporting each axle.

(c) Step Wells. Passengers shall not be permitted in the front step well of any bus while the vehicle is in motion.

(d) Seat Beside Driver. No more than two pupils shall be allowed to occupy the seating space beside the driver of a Type 2 school bus.

(e) Standing Passengers. A vehicle shall not be put in motion until all passengers are seated, and all passengers must remain seated while the vehicle is in motion. Standing passengers are permitted only on a bus (except a school bus, SPAB, or youth bus) operated in regularly scheduled passenger stage service or urban and suburban service by a common carrier or publicly-owned transit system, and equipped with grab handles or other means of support for standing passengers, and constructed so that standing room in the aisle is at least 74 in. high.

(f) Open Doors. While passengers are aboard, a vehicle shall not be put in motion until the doors are closed. The doors shall not be opened until the vehicle is stopped. The doors of a school bus shall be closed while the bus is in motion, whether or not there are passengers in the school bus.

(g) Emergency Exits. While a passenger is aboard, no bus or modified limousine shall be put in motion with any emergency exit locked or otherwise secured against being opened from the inside. While a passenger is aboard, no bus or modified limousine, equipped with emergency exits that are designed to be opened from the outside, shall be put in motion with such emergency exits locked or otherwise secured against being opened from either the outside or the inside. This paragraph shall not apply to buses operated by or under contract to law enforcement agencies while transporting persons in police custody.

(h) Interior Lighting. During darkness, the driver shall ensure that the interior lighting is sufficient for passengers to enter and exit safely and whenever otherwise deemed necessary.

(i) Ejection of Pupils. The driver of a school bus, youth bus, or SPAB shall not eject any school pupil unless the pupil is given into the custody of a parent or any person designated by the parent or school.

(j) Ejection of Pupils. The driver of a PAB shall not eject any school pupil unless the pupil is given into the custody of a parent or any person designated by the parent.

(k) Exemptions. The provisions of subsections (c) and (e) shall not apply to persons testing or training a driver, maintenance personnel, a sales or manufacturers' representative, or an adult acting upon a request by a school bus or SPAB driver to supervise or assist a pupil.