h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Here in Manchester, where a popular sport in some areas is Bricking The Streetlights, I've seen the debris from a well-bricked traffic light or two and it hasn't looked or felt like plastic at all - more like fragments of very thick coloured glass.

Small point of order in an otherwise interesting Entry!

Traveller in Time trying to catch up
"The entry does not say _all_ traffic lights are made of LEDs. It merely suggests they can be made of LEDs as the current colours match the colours defined by law.

The LED traffic lights I have seen so far are: pedestrian lights and stop lights in parking garages. "

Apologies: to express myself more clearly.

Traffic lights I've seen in a broken or partially dismantled condition appear to be made up of a plain but extremely strong light bulb, which like the ones you buy for domestic use is full-spectrum white light.

The colour component is provided by screwing a very thick coloured glass disc in front of it, be it red, amber or green. (This explains why the white bulb behind has to be big and high wattage - one thing I remember from physics lessons is that full-spectrum light is reduced to a seventh of its capacity when projected through a coloured filter, as six-sevenths of it is the wrong colour and will be blocked out)

These glass filters are only recognised for what they are if the traffic light is seriously damaged (hit by very big traffic impact) or vandalised (bricked out).

And when these coloured filters are seen in pieces on the ground where they might be picked up and examined more closely, they are certainly glass - no two ways about it - ratheer than plastic.

Traveller in Time on his head
"Just read the entry again.

Seeing red due to traffic light has nothing to do with the lightbulb of the traffic light. 'Parked' in the traffic jam between traffic lights you see red if all the cars in front of you push their break pedal.

At least that is how I experience traffic lights.

Some of these break lights have been exchanged to LEDs, using Pulse Widht Modulation to increase the brightness for breaking. Disadvantage: 'low' frequency ~50Hz blinking seems like a movement. "

Hi - I might be pi$$ed (just killing time before family gasthering at midnight) but when I last looked there were FOUR postings in this thread and not two.

So where did postings four and five from last night go to?

Traveller in Time looking up
"They went to the pub stayed there until this morning played some game with LASER LEDs and came home to this thread again . "