What three things do road signs do to promote the smooth movement of traffic?

Three things that road signs do to promote the smooth movement of traffic are:(1) Maintain speed with speed limit signs,(2) Prepare each driver for conditions ahead, such as curves and intersections, with warning signs, or preparing each driver for possible road hazards, allowing them to 'plan' ahead how they will handle situations, such as icy roads, flood areas, soft shoulders, etc., and(3) Advise drivers of exits and major intersections, allowing them to move to the appropriate lane before their exit comes along.