does anyone know if there is a sensor on traffic lights in order to activate the left green arrow only if there are cars waiting, and if it is sensitive to time (like depending on the number of cars waiting it takes longer?). If there is a sensor, where is it? Also, what about the light turning green for ambulances and police? Is the traffic light activated from the ambulance in question?
2006-09-08 06:48:34 · 7 answers · asked by dltscyc 2 in Education & Reference ➔ Trivia
Not all stop lights work the same but some are "weighted" which means that there is something in the concrete under the street that lets the light know when there is a car waiting there, it's basically a scale and if a car sits on the scale then the light will turn. Some lights always have a turning arrow, even if there are no cars there. If you get stuck at a light that should turn but doesn't then try moving up closer to the stop line because the scales are under the stop lines and if you wait too far back the car doesn't get registered.
Ambulances and police cars change the lights in some places or they can be changed by their dispatch center.
2006-09-08 06:54:57 · answer #1 · answered by Beccawho 3 · 0⤊ 0⤋
As far as I know, most of these things depend upon the model of traffic light, which differs from one city to the next. Older lights are usually operated independently and are on a timer. Newer ones may be part of a system, operated from a central location, and have more sophisticated ways of working. Different models might have sensors in different places. I've heard of lights being operated remotely by emergency vehicles, but I don't know if that was a story about what could be done in the future, an experimental system, or commonplace.
2006-09-08 06:54:39 · answer #2 · answered by neniaf 7 · 0⤊ 0⤋
Its below the street; (you can see a square drawed on the street in the left lane)
If a vehicles must turn left
It activates by weight, ....
If not the lights will switch
There are cameras in every busy crossroad, so in case of an emergency traffic lights can be controlled from a remote traffic station for ambulances and police
2006-09-08 08:03:10 · answer #3 · answered by spyblitz 7 · 0⤊ 0⤋
There are several different types of sensors used depending on the age of the lighting system. Pressure sensors under the turn lane. Radio Frequency sensors at the bottom of the poles, etc.
2006-09-08 06:57:44 · answer #4 · answered by luckyaz128 6 · 0⤊ 0⤋
There are 2 kinds of left turns: secure - Permissive. those do no longer have a red arrow indication. you may want to turn left on the golf eco-friendly arrow (secure) or on the golf eco-friendly ball (permissive - no longer secure). secure means there might want to no longer be any conflicting motorcar or pedestrian site visitors - besides the undeniable fact that it truly is not a assure. people violate alerts continually. Permissive means you may want to pay attention of conflicting pedestrian and vehicular site visitors. secure surely. those have a red arrow. you may't make a left turn except the golf eco-friendly arrow is displayed. A left turn on a eco-friendly ball indication isn't criminal in this concern. some jurisdictions will position a demonstration next to the signal head that announces "Left turn on eco-friendly Arrow surely" or "Left turn signal". in case you word a red arrow, you may't turn contained in the route of that arrow even as that's displayed. you may want to watch for the golf eco-friendly arrow indication.
2016-11-25 20:48:30 · answer #5 · answered by allotey 4 · 0⤊ 0⤋
there is an electrical cable that , run's under the street. if you look closely at the white line where, you are supposed to stop, there is usually a visible crack where the cable is buried. it is activated by, the metal in your car this is why sometime if, you are not close enough to the line, the light wont change.
2006-09-09 19:09:47 · answer #6 · answered by ny21tb 7 · 0⤊ 0⤋
yes there activated by the bright lights
2006-09-08 06:51:00 · answer #7 · answered by Anonymous · 0⤊ 0⤋