Traffic Lights. - Page 2

**Hugh** · 24-07-2006, 19:13

Quote:

Originally Posted by Felinix_Devotion

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?

TheDaddy · 24-07-2006, 19:20

Turns out it's not a myth after all http://auto.howstuffworks.com/question234.htm

altis · 24-07-2006, 19:21

Quote:

Originally Posted by Rob C

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, 19:50

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, 20:02

Quote:

Originally Posted by jtwn

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, 20:40

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, 20:53

Quote:

Originally Posted by Felinix_Devotion

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

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

Quote:

Originally Posted by altis

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, 21:38

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, 21:43

Quote:

Originally Posted by Mr_love_monkey

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, 21:44

Quote:

Originally Posted by Mr_love_monkey

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, 21:48

Quote:

Originally Posted by altis

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...

24-07-2006, 21:52

Quote:

Originally Posted by altis

Quote:

Originally Posted by Mr_love_monkey

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, 21:55

Quote:

Originally Posted by homealone

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, 22:02

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.

24-07-2006, 22:09

Quote:

Originally Posted by Mr_love_monkey

Quote:

Originally Posted by homealone

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