The Superintendent of Public Works may, upon notifying the Police Department and the Fire Department, close any street or public place or section thereof to public traffic for the purpose of repairing, constructing or reconstructing the same. When so closed, at the entrance to said closed portions, signs shall be posted indicating that the street is closed and that passing is forbidden. No person shall drive or cause to be propelled any vehicle over any street or portion thereof so closed when appropriately marked.