How do traffic lights work? Sensors, timing, connection with other traffic lights … the whole shebang.
In: Technology
At the most basic level, the traffic lights have a pre-programmed controller. The controller tells the light how long to show each colour to each direction. If the controller is a bit fancier, it will allow the program to be different at different times of the day or different days of the week.
Most traffic lights have detector loops in the pavement (they look like big black circles.) The detector loops are coils of wire that develop an electric current through induction when the metal frame of a car is above them. The controller would adjust the program for when cars are present – for example you might have a green light that only lasts 10 seconds, but it stays green when cars are coming up to a maximum of 30 seconds.
Very fancy traffic lights use cameras instead of coils, and they could be networked with other controllers in the city. That would allow for things like setting up a “green wave” for emergency vehicles.
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