Car enclosures shall be:

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

(2) Enclosed with a type of material that will reject a 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 3/4 in. or above 1 in.;

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