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STONEISLAND
24-07-2006, 15:31
Do they get managed? EG on approach they turn red, no cars coming from the other direction on red for no reason? Do they have sensors on them? They should do. I'm sure a lot of our traffic problems and road rage would end if traffic lights where managed properly. Surely its not that hard?

Another EG, big queue waiting for green, across the road one car goes across and that's it. And were still waiting?

Is it just me??? Just does not seem to make sense to me?

Chrysalis
24-07-2006, 15:34
I think some lights do have sensors, but they primarily used at night time at quiet times of the day. During busy periods they are more on a timed interval, since the sensors would be overwhelmed with constant flow of traffic.

I also believe ones near hospitals can be controlled by emergency services when they are approaching them.

STONEISLAND
24-07-2006, 15:38
I think some lights do have sensors, but they primarily used at night time at quiet times of the day. During busy periods they are more on a timed interval, since the sensors would be overwhelmed with constant flow of traffic.

I also believe ones near hospitals can be controlled by emergency services when they are approaching them.

I could do with one of them.

You will proberbly know Abbey Lane prime example of dogey lights. The build up of traffic is really bad along there just because of the timing of lights.

fireman328
24-07-2006, 15:39
As far as I know some are electronically by traffic flow but others are on a timed sequence, hence you can wait ages at red lights at night even though no other traffic is at the lights going in any direction. Lights at pedestrian crossings also take longer to change.

homealone
24-07-2006, 15:43
http://www.its.leeds.ac.uk/facilities/icity/facilities/scoot.htm

TheDaddy
24-07-2006, 15:47
I seem to remember some one telling me that some are light sensitive, like the ones they use when digging up the road, once they have gone home apparently they will change if you flash your lights at it, I have tried it and it does seem to work although I feel there is a fair chance that it's just coincidence.

orangebird
24-07-2006, 15:53
I seem to remember some one telling me that some are light sensitive, like the ones they use when digging up the road, once they have gone home apparently they will change if you flash your lights at it, I have tried it and it does seem to work although I feel there is a fair chance that it's just coincidence.

My other half works in Lighting Services for the SEC - these type of traffic lights don't exist anymore. They're on timers only.

AndrewJ
24-07-2006, 17:46
I would think a shotgun would be a good method of controlling the lights. ;)

Stuart
24-07-2006, 17:49
I seem to remember some one telling me that some are light sensitive, like the ones they use when digging up the road, once they have gone home apparently they will change if you flash your lights at it, I have tried it and it does seem to work although I feel there is a fair chance that it's just coincidence.

My other half works in Lighting Services for the SEC - these type of traffic lights don't exist anymore. They're on timers only.


Are you talking about the roadworks lights? There is a (relatively new) set of permantly installed lights near me that do react to the presence of traffic.

MovedGoalPosts
24-07-2006, 17:59
Many traffic lights do react to traffic to adjust the timings. Look at the road surface, the thin black tarmac boxes, diagonals are electronic field sensors that can detect if a car is over them. Great for vehicles to trigger a light change, but useless if your on a pushbike :(

All the sensors will do is speed up a change if there is nobody going from a certain direction. The lights will have a maximum setting they will stay green on a direction, in part to stop traffic congestion elsewhere.

keithwalton
24-07-2006, 18:10
My other half works in Lighting Services for the SEC - these type of traffic lights don't exist anymore. They're on timers only.
Really as there are some road works near me which has lights with sensors mounted on the top of them and they changed on demand for me the other day.

In answering do traffic lights have sensors / control systems the answer is yes!

In fact most of Hampshire's permenent lights run on the RoManSe system these days (http://southampton.romanse.org.uk/) they are computer controlled and are adaptive to traffic levels and auto adjust for congestion levels. Under the road just before the lights are pressure sensors, if at night the lights are red you can approach the lights and they will automatically change for you in most cases. If there is other traffic they may hold you for a few seconds but the more cars going your way the sooner they will change, especially if a vehicle is static over the sensor.
They all report into a central computer system which relays real time data to that website (if you zoom in close enough you will see lines of different colours depending on the triggered traffic level).

They also have cameras on many of the busy junctions so if you enable the cctv option you can see what the traffic is like.

I guess southampton needs this kind of sophistication since it does hard the 3rd highest density of traffic lights in europe i believe

Stuart
24-07-2006, 18:18
Do they get managed? EG on approach they turn red, no cars coming from the other direction on red for no reason? Do they have sensors on them? They should do. I'm sure a lot of our traffic problems and road rage would end if traffic lights where managed properly. Surely its not that hard?

Another EG, big queue waiting for green, across the road one car goes across and that's it. And were still waiting?

Is it just me??? Just does not seem to make sense to me?


AFAIK, traffic lights in most towns and cities are controlled by a central computer. As discussed above, they may have sensors (or even cameras in the case of those in London) that are used to adjust the timings as appropriate for the traffic conditions.

Shaun
24-07-2006, 18:33
I don't know why we don't do the same as in Spain and put the lights on flashing amber (where it's safe) after a certain time so people can just make their own mind up when to go. Makes so much sense to me!

Russ
24-07-2006, 19:13
Flashing your lights at traffic lights to get them to change is a fallacy but people still vainly try it for some reason. If there's a sensor on top it might work but for normal lights, it won't.

AndrewJ
24-07-2006, 20:01
I wonder though with this myth.

When you approach a pelican crossing, if you push the button and rotate your finger 90* to the right the lights change quicker.?

Hugh
24-07-2006, 20:13
I wonder though with this myth.

When you approach a pelican crossing, if you push the button and rotate your finger 90* to the right the lights change quicker.?

How would you reach the button from your car? :monkey:

TheDaddy
24-07-2006, 20:20
Turns out it's not a myth after all http://auto.howstuffworks.com/question234.htm

altis
24-07-2006, 20:21
Many traffic lights do react to traffic to adjust the timings. Look at the road surface, the thin black tarmac boxes, diagonals are electronic field sensors that can detect if a car is over them. Great for vehicles to trigger a light change, but useless if your on a pushbike :(
I once worked on the traffic monitoring system for the Conway tunnels on the A55. The sensors are just a coil in the road surface and work at a fixed frequency (IIRC it was 100 and something hertz). They monitor traffic by noting the change in inductance of the coil. Some guy from the manufacturer said that the best place to ride a bike is about 1 foot in from the corner of the diamond.

All fixed traffic lights have vehicle sensors - mostly these inductive road loops whilst temporary traffic lights use dopler radar. The lights in Warrington are now all linked together (each set has a little aerial somewhere). The theory is that the central computer can override the timing to maximise the traffic flow. I can't say I've noticed the difference though.

The best bit of highway technology I've seen are intelligent cats eyes. There's some on the A590 out to Barrow-in-Furness. They are solar powered and actually light up when a car comes by. If you switch your lights off they'll carry on glowing and you can even see them flickering as they talk to each other. Some can even change colour when the road gets below freezing temperature. How cool is that!!!

jtwn
24-07-2006, 20:50
I do believe that trunk roads that pass villages that have lights would just have it permanently on green til something passes over the sensors from the approach to the lights from the village.

altis
24-07-2006, 21:02
I do believe that trunk roads that pass villages that have lights would just have it permanently on green til something passes over the sensors from the approach to the lights from the village.
I forget the name of it now but some even have a speed trip so that, if you're at or over the speed limit, the lights will turn to red.

SnoopZ
24-07-2006, 21:40
The ones in my village have sensors ontop that will change them to green when i approach and there are no other cars waiting anywhere. It took me ages to work out why it used to go from green to red to green again in about 2 seconds until i spotted the sensors.

MovedGoalPosts
24-07-2006, 21:53
I wonder though with this myth.

When you approach a pelican crossing, if you push the button and rotate your finger 90* to the right the lights change quicker.?

Some people will beleive anything :D

---------- Post added at 20:53 ---------- Previous post was at 20:51 ----------

Some guy from the manufacturer said that the best place to ride a bike is about 1 foot in from the corner of the diamond.

Excellent, and where is the corner of that Diamond located - often somewhere that no sensible cyclist who values his life would ever be :(

Mr_love_monkey
24-07-2006, 22:38
On the subject of traffic lights... why do they put those mesh grills over the green lights? (including the green man)

Hugh
24-07-2006, 22:43
On the subject of traffic lights... why do they put those mesh grills over the green lights? (including the green man)

Stop the electricity escaping

altis
24-07-2006, 22:44
On the subject of traffic lights... why do they put those mesh grills over the green lights? (including the green man)
I think they're called collomators and are so they can only be seen from one direction.

Mr_love_monkey
24-07-2006, 22:48
I think they're called collomators and are so they can only be seen from one direction.
hmm. makes them difficult to see in any direction... in my opinion...

homealone
24-07-2006, 22:52
On the subject of traffic lights... why do they put those mesh grills over the green lights? (including the green man)
I think they're called collomators and are so they can only be seen from one direction.

http://en.wikipedia.org/wiki/Collimating_lens

Mr_love_monkey
24-07-2006, 22:55
http://en.wikipedia.org/wiki/Collimating_lens
Hmm.. still can't really see the point of them, other than to wind me up

altis
24-07-2006, 23:02
I think they're supposed to be for the numpties who are not paying attention and don't clock which traffic light is intended for them.

homealone
24-07-2006, 23:09
http://en.wikipedia.org/wiki/Collimating_lens
Hmm.. still can't really see the point of them, other than to wind me up


how can something be parallel & 'wind you up' :)

- we have traffic lights based at the end of a flyover, here, which has a pelican crossing 10 meters past where the main lights are situated. Fitting collimating gratings to the lights on the pelican means you don't get confused between the two, as they are designed so you don't see the pelican lights before the main ones, so it can work :)

Creative
24-07-2006, 23:13
The ones in my village have sensors ontop that will change them to green when i approach and there are no other cars waiting anywhere. It took me ages to work out why it used to go from green to red to green again in about 2 seconds until i spotted the sensors.

As already said, the sensors work inductively. They are embedded in the road. The lights changing coincides with you passing over the inductive loop.
The sensors ontop of the lights are indeed light sensitive, but they are there to reduce the amount of electrickery the lights need to use. When its dark, the lights are more visible and therefore the supply current can be reduced.

Anonymouse
25-07-2006, 00:06
I wonder though with this myth.

When you approach a pelican crossing, if you push the button and rotate your finger 90* to the right the lights change quicker.?
What, you mean the pelican crossings in your area actually work? That is, do they change the lights when you as a pedestrian press the button?

I ask because there are several in Bolton, especially at junctions in or near the town centre, which seem to be no more than a sop to the pedestrian. One early evening when there was virtually no-one about (and therefore the pelicans hadn't been used in a while), I watched the sequence of lights for several minutes...and discovered by experimenting that it doesn't make a blind bit of difference whether you press the bloody button or not - the pelican crossing is included in the sequence.

Years ago, if you came to a crossing that'd just been used, it'd take a few minutes to work, whereas if it hadn't been used for several minutes it'd respond immediately. But not any more, it seems - certainly not in Bolton. The crossings near Trinity Street train station and Sainsbury's don't work as pelican crossings are supposed to. Granted, if they did traffic would be stopped from several different directions, but I find it annoying that they're misrepresented as pedestrian crossings when they're really nothing of the kind. The crossings at St. George's Road/Knowsley Street are the same - the sequence is: red lights one way for about 20 seconds; red the other way for 20; red both ways for 20. Your pressing the button has no effect whatsoever on this sequence.

They also give a false sense of security to people who don't realise this - I've seen people pressing the button and expecting the crossings to react more or less straight away. It's a wonder people aren't being killed every day. The buttons should be removed; IMO they're actually a danger to the public.

Has anyone else noticed this phenomenon in their area?

MovedGoalPosts
25-07-2006, 00:42
A few of our traditional pelican crossings, those with the flashing amber (go if the crossing is clear) lights have been modernised. No falshing amber anymore. All that means is traffic now sits there for an eternity granny has crossed and is halfway up the street before cars can move. And they wonder why at peak hours we have traffic jams stretching back to the next town. So much for progress :mad:

Chrysalis
25-07-2006, 04:38
if the traffic lights are normal ones for junctions that have the pedestrian crossings then the pedestrian part is sometimes part of the timer but not always. Where I live now there is some down the road which I think are fixed timers, they include the pedestrian crossing which adds to the queues since there isnt always pedestrians. However nearer where I used to live there is another junction which primarily uses sensors for its traffic since its a quieter junction, and the pedestrian crossing only goes green when the button is used. It could be that at night time the timer versions become intelligent and use sensors plus the buttons but in the day its fully timed.

ZrByte
27-07-2006, 11:43
Many traffic lights do react to traffic to adjust the timings. Look at the road surface, the thin black tarmac boxes, diagonals are electronic field sensors that can detect if a car is over them. Great for vehicles to trigger a light change, but useless if your on a pushbike :(


And with some light motorcycles. I remember myself and a friend about 3 years ago having to back up over one of the pressure sensors and jump up and down on our bikes for a second before we could get the light to change.

Creative
27-07-2006, 22:58
And with some light motorcycles. I remember myself and a friend about 3 years ago having to back up over one of the pressure sensors and jump up and down on our bikes for a second before we could get the light to change.
They aren't pressure sensitive. Its an inductive loop, your metal vehicle disturbs the magnetic field within the loop. Hence why bikes are less effective than a large metalic car.

Chrysalis
28-07-2006, 04:32
Every roadwork traffic lights I have seen have some kind of sensors, usually laser thing located above the red light, there was some on the road outside my house today that werent working quite right and one of the workmen ended up directing the traffic after police came informing them the queue was 2 miles long :).

Nidge
28-07-2006, 19:11
Do they get managed? EG on approach they turn red, no cars coming from the other direction on red for no reason? Do they have sensors on them? They should do. I'm sure a lot of our traffic problems and road rage would end if traffic lights where managed properly. Surely its not that hard?

Another EG, big queue waiting for green, across the road one car goes across and that's it. And were still waiting?

Is it just me??? Just does not seem to make sense to me?


Like whats been said all traffic lights have senors on them but they only work when the traffic has died down like at night times, when I was on the taxis you could hit every green light at 3 in the morning because the sensors picked you up. If you look down at the tarmac when your sat at a set of lights you'll see some markings where the sensors are, when you run over them at a night time the lights change for you.

MovedGoalPosts
28-07-2006, 20:42
Like whats been said all traffic lights have senors on them but they only work when the traffic has died down like at night times, when I was on the taxis you could hit every green light at 3 in the morning because the sensors picked you up. If you look down at the tarmac when your sat at a set of lights you'll see some markings where the sensors are, when you run over them at a night time the lights change for you.

You haven't driven round Staines in the wee small hours then. The lights seem to be designed to sense you coming and turn red:mad:

ZrByte
29-07-2006, 01:47
You haven't driven round Staines in the wee small hours then. The lights seem to be designed to sense you coming and turn red:mad:

I found the same thing driving through Liverpool city center in the early hours yesterday morning.
I love driving through my home town as I get the exact opposite and get nothing but green lights but last night was a nightmare, it took about 10mins extra on a 40min trip just because of the amount of time I spent sat at red lights while nothing went by in the opposite direction.

Nidge
29-07-2006, 15:20
You haven't driven round Staines in the wee small hours then. The lights seem to be designed to sense you coming and turn red:mad:



Lol well the lights work ok in Mansfield.:D

Gareth
29-07-2006, 15:45
Like whats been said all traffic lights have senors on them but they only work when the traffic has died down like at night times, when I was on the taxis you could hit every green light at 3 in the morning because the sensors picked you up. If you look down at the tarmac when your sat at a set of lights you'll see some markings where the sensors are, when you run over them at a night time the lights change for you.

You haven't driven round Staines in the wee small hours then. The lights seem to be designed to sense you coming and turn red:mad:Rob, that's the Bling Sensor that they had to install in all traffic lights across Staines that is causing this to happen ;)

MovedGoalPosts
29-07-2006, 15:47
What you mean if you don't have bling you get stopped :(

Stuart
29-07-2006, 23:33
Just to complicate things a little further, they are currently installing a system in London that changes the prioty of Traffic lights when Buses approach. A similar system is already in place in Croydon (basically, the Croydon tramlink takes priority over any other road traffic).

http://www.buspriority.org/overview.htm

bob_a_builder
30-07-2006, 00:14
Great for vehicles to trigger a light change, but useless if your on a pushbike
No one else picked up on the novelty value of a cyclist actually stopping at a red traffic light anyway

MovedGoalPosts
30-07-2006, 01:07
Great for vehicles to trigger a light change, but useless if your on a pushbike
No one else picked up on the novelty value of a cyclist actually stopping at a red traffic light anyway

Maybe that's why they don't stop. Tit for tat if lights don't recognise cyclists why should cyclists recongnise traffic lights :spin:

Theodoric
01-08-2006, 22:13
Flashing your lights at traffic lights to get them to change is a fallacy but people still vainly try it for some reason. If there's a sensor on top it might work but for normal lights, it won't.
Sounds like those people at pedestrian crossings who, although the little box is already showing WAIT, will keep on pressing the button in the fond hope that this will speed things up.