Traffic Lights

[barney4444]

When stopped at temporary traffic lights at night (Road works etc) you often see people flashing their lights at the red light to make them change to green quicker. Does this actually achieve anything or are the lights just changing on a fixed time sequence?

[EDDIE51]

Another urban myth flashing your lights does nothing at all to the traffic lights. They are on a timed sequence . Some lights have a traffic detector that senses an approaching car and changes the lighs to let it passed if the traffic is very light, for instance in the early morning, but even then flashing your headlights does nothing as it is a movement sensor similar to those door lights you see that come on when someone gets close.

[ummmm]

They are either on a fixed time or vehicle radar. Nothing you do will hurry them up if they are on fixed time.

[Old_Geezer]

You may often see it, I never have.

If it achieves anything it is a false sense of control given to the driver who may then continue their journey in a slightly less dark mood than they otherwise would.

What I want to know is that given that it is now 2012, how come we still have traffic lights that appear to sense your imminent arrival so they can go red and hold you up, until someone comes along in the other direction and then the lights change apparently to hold them up ? Surely by now we can expect (artificially) intelligent behaviuor from our lights ? Or how about the number of times, when no traffic is about, the lights opt to switch for no apparent reason so the direction least likely to produce the next car is at green ?

[baza]

o-g i thought that only happened to me. nice to know other people get caught out as well.

[TWR]

There is a sensor on top of the lights, & yes flashing at the Sensor does change the lights if the other side is clear.

[hc4361]

No, it doesn't, TWR.

The sensor knows you are there, whether you flash your lights or not.

[baza]

b***** sensor never seems to sense me, i think they have a mind of their own.

[TWR]

That's Strange Hc, there are some road works near an area I drive through, its on a blind bend, as I approach the Temp lights are on Red, as soon As I flash the lights they change!

[Baldric]

^^^ motion sensor ^^^

[naomi24]

I've never seen anyone flahsing their lights at temporary traffic lights. Never heard of it either.

[sddsddean]

I've worked with roadworks in one capacity or another for over 25 years TWR and you definately cannot change the lights by flashing at them. They are microwave sensors on top of the lights (so work on a wavelength of around 10cm) whereas wavelength of light is a bit shorter than that!!, so no effect. The sensors have probably detected you at the same time you flash your lights...its coincidence.

[woofgang]

me either.

[MantaRay]

The sensors detect your vehicle, not the lighting.

[Mobius1]

Old_Geezer - I don't know about expecting semi-intelligent automation from traffic lights. The ones in the area I live always seem to be failing. They want to make the dumb ones reliable before they start making them adaptive.

[BillyBB]

i thought it was an urban myth that some TTL detected the flashing lights of an emergency vehicle and gave priority.
If this was true then everyone would be flashing their lights all the time so no use for the ambulances anyway.

[ummmm]

You are wrong TWR. My OH puts temp traffic lights up on a daily basis. They either have a sensor (if they're going to be there for more than a few days) or are timed.

[Prudie]

I always flash a sensor set near me that manages single file under a railway bridge. It just makes me feel better.

[ChuckFickens]

Old traffic lights in America did detect flashing lights to detect emergency vehicles approaching, but this system has never been used in this country, also they detecting strobe lights, not slowly flashing lights, so you wouldn't have been able to trigger even the old American lights unless you could flash your headlights at more than about 15 times a second.