Filter traffic lights allow specific flows of traffic to proceed while other directions must stop, permitting multiple traffic movements at the same time. They are often used to allow right (or left, depending on the country) turns while other traffic continues straight or turns the opposite direction.
Here's a breakdown of how they function:
- Specific Direction Control: Filter lights are designed to control traffic turning in a specific direction, usually to the right (or left).
- Simultaneous Movement: They allow vehicles turning in the filtered direction to proceed even when the main traffic light is red for other directions of travel. This facilitates smoother traffic flow.
- Stopping Other Traffic: When the filter light is active for the turning traffic, the main light will be red for other directions, ensuring that conflicting traffic stops, making the turn safer.
- Increased Efficiency: Filter lights are added to intersections when traffic analysis shows a need to allow for turning movements to proceed without significantly disrupting the main traffic flow. They contribute to increased efficiency and reduced congestion at intersections.
- Common Use Case: A very common scenario is where a filter light allows right-turning traffic to proceed, while traffic going straight or turning left must wait for a green light or arrow.
In essence, filter lights optimize traffic flow by safely permitting specific turns concurrently with other traffic movements, reducing overall waiting times at intersections.
