It shall be unlawful for any railroad company, or its employees, operating or running trains through the city to blow or have blown the whistles of the engine of such train, except at each railroad crossing or for the purpose of blowing for the board of semaphore as required by state law, the rules of such railroad or in case of emergency as additional warning of any impending danger to life or property.
(`87 Code, § 17-361) Penalty, see § 70.99