Traffic lights are coloured lights that are used to control traffic flow. They instruct traffic when it must stop (usually a red light) or may proceed, or continue to proceed (usually a green light). In some countries intermediate lights (usually amber) may also be used when changing from Stop to Go or from Go to Stop.
Questions tagged [traffic-light]
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What are the pros and cons of a traffic circle versus a traffic light intersection?
The debate of traffic circles (also called roundabouts or rotaries) versus traffic light intersections has been in progress for a while. Those in favor of traffic circles say that, among other things, that they are safer than traffic light…
APerson
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How does a traffic light sense the proximity of vehicles?
Some traffic lights don't operate periodically but instead detect when a car is close by and then turns green. I have heard that they use a magnetic sensor embedded in the road to sense cars as they come near. Is this correct? Do they use other…
FullmetalEngineer
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How are train crossing signals and highway traffic signals coordinated?
Some roadway intersections that are near railroad tracks have signs that light up when a train is approaching. These signs warn that certain turns are not allowed because of the train. One of these signs is shown below from the City of Edmonton.
My…
hazzey
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What is the starting/stopping sequence of a traffic light
As is probably known a traffic light may be turned off in which case normal rules applies to the intersection.
While the traffic light is active then red & red+yellow means that drivers are required to stop, while green means that the drivers are…
skyking
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How can traffic signal controllers handle multiple conflicting preemption requests of equal priority without dropping one?
Let us assume that we are North American traffic engineers, and have the (hypothetical, plausible, yet pathological) intersection configuration depicted (not to scale and lacking lane lines, sorry -- I did not have time to build the model to scale…
ThreePhaseEel
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Where to acquire / create LED optics
I'm working on a few projects that require lenses to focus LED light flashes, similar to those lenses used by police lights (TIR lens) and other strobe traffic lighting utilizing Fresnel lenses. I've scoured the internet and cannot find anyone…
Zero
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How can a sensor detect the traffic lights?
I am working on an idea for my capstone project. I am trying to get an idea of a device, sensor or reader that can detect the front traffic light situation. so that it can tell when the light is green or red. I am still not sure what is the best way…
Almarhoon
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What color do green traffic lights have?
A friend of mine who is (completely) red/green color blind once told me that he can distinguish the green traffic light from the yellow and red one despite his color blindness and that he thinks to be able to remember having heard that this is not…
zvavybir
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How do "Your Speed" Signs work, and how do vehicles know when it's the sign's turn to display their speed?
I see these LED speed signs on the side of the road, which display the approaching vehicle's speed.
What I have gathered is that they measure the time between the sending and receiving of the signals and then convert it into distance. My questions…
Ritika Das
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What are the disadvantages of free-flow intersections?
I've recently learned about free-flow intersections. In particular, the DCMI, and the Stack interchanges.
What are the disadvantages of using them, compared to the "normal" signaled intersections? do they cost significantly more?
mbrg
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Adding traffic lights to a junction, what is the logic of using lights with arrows?
I'm doing a job and one of the feature is adding realistic traffic lights to junctions of a network and I have to be very specific. So, if on the ground there are arrows signaling the traffic flow (e.g., one for right turn and two for straight…
