It shall be unlawful for the driver of any vehicle to disobey the instructions of any traffic sign or signal placed in view by authority of the City Council or in accordance with the laws of the State of Illinois, excepting on direction of a police officer. All signs and signals established by direction of the government shall conform to the State Manual of Uniform Traffic Control Devices for Streets and Highways. (M.C. 1962, sec. 18.104)