Car enclosures shall be:

(1) Enclosed on all sides, except at the entrance, to a height of at least 1066.8 mm (42 in.);

(2) Enclosed with a type of material that will reject a 38.1 mm (1.5 in.) diameter ball;

(3) Securely fastened to the car platform so that it cannot become loose or displaced due to ordinary service, application of the car safety, or car contact with a buffer;

(4) Built to withstand a 75 lb. pressure, horizontally applied at any point on the wall, without causing a wall deflection that reduces running clearance below 19.05 mm (0.75 in.) or above 25.4 mm (1 in.);

(5) Weather resistant plastic and tempered safety glass may be used in car enclosures.