Whenever the Police Chief shall deem it advisable for the public safety or convenience temporarily to close any street, alley or part of a street to vehicular traffic, or to vehicles of any particular description, or to divert or direct the traffic thereon, or to direct or divert the course of pedestrian travel, he shall have power and authority to do so by the erection of proper signs. No person shall fail, neglect or refuse to comply with any such sign so erected.