It is unlawful for the directing officer or the operator of any railroad train to direct the operation of, or to operate, the same in such a manner as to prevent the use of any street for purposes of travel for a period of time longer than five (5) minutes, except that this provision shall not apply to trains or cars in motion other than those engaged in switching. This section shall not apply in case of engine failure or train accidents within the city limits. (1985 Code § 15-537)