All official traffic signs and signals existing at the time of the adoption of this code, such as stop signs, caution signs, slow signs, no-reverse-turn signs, signs designating time limits for parking or prohibiting parking, lines painted or marked on streets or curbs designating parking areas or spaces, markers designating loading zones, parking meters, and all other official traffic signs or signals erected, installed or painted for the purpose of directing, controlling and regulating traffic are approved. (Prior code § 6.025)