Traffic Lights for public transport
Traffic lights for public transport often use signals that are distinct from those for private traffic. They can be letters, arrows or bars of white or colored light.
In Portland, Oregon, the tram signals feature a horizontal white bar and an orange vertical bar. Some systems use the letter B for buses, and T for trams.
In Russia traffic signals for public transport have four white lights that form the letter T. If the three top lamps are lit, this means “stop”. If the bottom lamp and some lamps on the top row are lit, this means permission to go in a direction shown. If there are no tram junctions on an intersection, a simpler system of one amber signal in the form of letter T is used instead; the tram must proceed only when the signal is lit.
In North European countries the tram signals feature white lights of different forms: “S” for “stop”, “—” for “caution” and arrows to permit passage in a given direction.
The Netherlands use a distinctive “negenoog” (nine-eyed) design shown on the top row of the diagram; bottom row signals are used in Belgium and France. The signals mean (from left to right): “go straight ahead”, “go left”, “go right”, “go in any direction” (like the “green” of a normal traffic light), “stop, unless the emergency brake is needed” (equal to “yellow”), and “stop” (equal to “red”).