(a) The Director of Public Safety is granted emergency power to prohibit all vehicles, either for commercial or pleasure purposes or for both, from making use of any street which, in his opinion, is in such poor condition as to warrant its temporary closing.
(b) This same power is granted to the Director of Public Safety when, in his opinion, it is necessary to shut off vehicular traffic from a street because of the dangers incident to fire, flood, collapse of a building, police action, snow, ice, enemy action or because such a street or part thereof has been temporarily placed into use for recreational purposes.