No person in charge of any locomotive engine shall cause or allow the cylinder cock or cocks, safety valve or other valves of any locomotive engine to be opened so as to permit steam to escape therefrom at any time while running upon or along any railroad track where the engine is within 100 feet of any street or railroad crossing or viaduct. Provided, however, that when any such engine shall be standing at any such place in said city, and for six revolutions of the driving wheel after being put in motion, the said cocks may be opened for the purpose of allowing condensed steam to escape.
(Prior code § 188-46)