Okla. Stat. tit. 40, § 40-188: Equipment

On and after April 15, 1958, it shall be unlawful for any

person, firm or corporation operating or controlling any railroad

running through or within the State of Oklahoma and engaged in the

business of a common carrier to operate a track motor car, or

transport its employees in a track motor car, which is not equipped

with a substantial top for the protection of said employees from

rain, snow, sleet and hail, and equipped with a transparent

windshield sufficient in width and height to protect said employees

therefrom, which windshield shall be of safety glass. Such a motor

car shall also be equipped with an electric windshield wiper that

will remove rain, snow and other moisture from the windshield

thereof, and said windshield wiper shall be so devised that the

driver of said motor car can start or stop said windshield wiper

while he is driving the same.