How do traffic lights time or decide when to display their colors (red/green/yellow)?
In: Technology
as far as I know there’s 2 common methods for it; a simple timer, and pressure plates.
The timer method is just that – there’s a timer set up for how long to have each light be red or green, and that’s pretty easy to do with some programming. They do have to still be programmed (and that needs to be in it’s own weather/water proof box somewhere near the intersection), and how they decide at how long to program each light change usually involves researching how much traffic uses that intersection.
Pressure plates are used when it’s not *that* busy of an intersection, or they want to favor one of the roads more than the other, only changing it’s light when the pressure plate detects the weight of a car above it. Again someone still needs to program how long to have the lights change for – but instead of being on a clockwork timer, it’s only going to change the lights when the pressure plates send a signal.
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Some newer camera detection methods exist too, that are pretty much doing the same thing as pressure plates, but instead of needing to install a pressure plate switch under the road, they can use cameras instead, which are a lot cheaper to install, and relatively easy to maintain. They’re still operating on the same kind of basis as the pressure plate method – only change the light when it detects cars – just doing it with a different sensor.
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