(1) This section and sections 13 to 21 apply to both type I and type II school buses except where specifically provided otherwise.

    (2) A type I school bus shall have an outside body width of not more than 102 inches; an outside overall length of not more than 45 feet; and an inside height of not less than 72 inches, aisle floor surface to ceiling. A type II school bus shall have an outside body width of not more than 102 inches and an inside height of not less than 60 inches, aisle floor surface to ceiling.

    (3) A bus shall be attached firmly to the chassis. A spacer shall be inserted between the body and the frame at every point of contact so that shearing stresses are not put on rivet heads.

    (4) A bus floor shall be of metal at least equal in strength to 14-gauge steel and constructed and maintained so that exhaust gases cannot enter the bus. The floor, including wheelhousing, aisle, and stepwell, shall be covered and maintained with a slip-resistant surface. Floors shall be coved to the walls. All closures between the body and the engine compartment shall be fitted with gaskets that effectively prevent gas from entering the body. The bus body floor, cross members, and skirts shall be completely undercoated. A transmission inspection plate, if any, need not have a slip-resistant surface but shall be firmly attached.

    (5) Sedan-type doors shall not be used on type I school buses. When a jackknife-type service door is used, it shall fold forward toward the front of the bus. If a split-type service door is used, it shall open outward. Sedan-type doors may be used on service entrances of type II buses. The steps of a service door entrance shall be covered with 3/16-inch molded ribbed rubber or other nonslip surface.

    (6) An emergency exit shall be provided as follows:

    (a) Type I school bus: the upper and lower portion of the central rear emergency door shall be equipped with approved safety glass. The door shall be hinged on the right side and the door handle located on the extreme left. Piano hinges shall not be used. The handle shall be in the vertical position when latched. A locking device of any kind shall not be attached to, or made a part of, the emergency door unless the locking device meets all of the following criteria:

    (i) The device is integrated into the ignition system.

    (ii) The device is tamper resistant.

    (iii) The device has an audible alarm system.

    (iv) The device has an audible alarm near the driver's seat that will sound when the door is locked and the ignition is on.

    (b) Type II school bus: subdivision (a) applies to type II buses except that double rear emergency doors may be used. A double rear emergency door shall have a 3-point latch.

    (7) A bus body shall be lined with fiberglass or a comparable nonsettling, nonabsorbent insulation.

    (8) Book racks shall not be installed in a school bus.

    (9) The electrical system shall be 12 volt D.C. provided through an alternator with a minimum of 100 amp rating and a minimum battery storage capacity of 500 CCA with gasoline engine, or 900 CCA with diesel engine provided through 1 12-volt battery, 2 12-volt batteries, or 2 6-volt batteries. There shall not be an opening through the floor of the bus to service the battery.

    (10) All baggage, articles, equipment, or medical supplies not held by individual passengers shall be secured in a manner that assures unrestricted access to all exits by all occupants, does not restrict the driver's ability to operate the bus, and protects all occupants against injury resulting from falling or displacement of any baggage, article, or equipment. Oxygen cylinders secured to a wheelchair shall be considered to be in compliance with this subsection if they do not impede access to any exit.