No person shall cause or permit any railway train or railway cars or similar vehicle on rails to stop or stand or to be operated in such a manner as to prevent the use of any street for the purposes of travel for a period of time longer than ten minutes, except that this provision shall not apply to railway train cars or similar vehicles on rails while blocking or obstructing a crossing because of an accident which requires the operator of the train, car or similar vehicle on rails to stop at or near the scene of the accident. (Ord. No. 938, § 1.)