It is unlawful for any railroad operating in the city to cause or permit any engine, car or train to cross East "D" Street or Washington Street at its or their intersection with Hopper Street, or with any side tracks, spurs or switches, or to cross Washington Street at its intersection with Copeland Street, between the hours of seven a.m. and seven p.m., without protecting such points during the crossing thereof by a flagman, or such mechanical warning device as may be approved by the public utilities commission of the state. (Ord. 132 NCS §2; prior code §21.14.)