chapter 3 — signs, signals and road markings 37 Traffic lights Traffic lights are used to help organize the flow of traffic. Generally, a red light means “stop,”  a yellow light means “caution” and a green light means “go.” These signals can have slightly  different meanings if they are flashing or if they are shaped as arrows rather than circles. In some  places green arrows may flash; in others they may not.  Steady red — stop —  after coming to a full stop,  you may turn right or turn  left onto a one-way street  unless a sign forbids it Steady green — continue  if the intersection is clear Steady yellow — slow  down and stop before  the intersection unless  you can’t safely stop in  time Flashing red — stop, then continue only when it is safe  Flashing green —  pedestrian-controlled  light — go only if the  intersection is clear  Flashing yellow — slow  down and proceed with  caution Green arrow — turn in  the direction of the arrow Green arrow — no turn  permitted; go straight  through only Flashing green arrow  with a steady green  light — may turn in the  direction of the arrow or  proceed Flashing green arrow  with a steady red light —  left turn allowed; through  traffic must stop for red  light Yellow arrow — advance  left turn signal is about  to change, slow down  and stop before the  intersection unless you  can’t safely stop in time Transit priority signal —  steady white rectangular  light — only buses may  go on this signal