Can anybody else remember blue traffic lights on railways? Can't find any evidence on google. I'm sure whereas cars have red/amber/green, railways always had a 4th blue light. What does it mean and why has it disappeared from Google?
Never heard of it.
4 (& 5)-aspect signals have always had red, green and two ambers as far as I know.I know that the semaphore signals had lenses that were red and blue, but they definitely showed as red and green when lit from behind by yellowish oil lamps at night.
SteveW
Two possibilities but the first doesn?t really fit with your interpretation of a 4 th aspect. The glass in semaphore signal arms could be seen as blue if viewed in a certain light as the the lens was a bluish glass to when illuminated at night from an oil lamp or in later years a lowish watt electric lamp the yellow flame /filament colour combined with the blue to indicate green. The other is that you have seen or are referring to somewhere other than the UK where blue is sometimes used.
GH
The glass in green traffic signals used to look blue to me - when they had the dual-filament tungsten lamps.
This was definitely in the UK, and I remember it as a lit blue electric lamp, one of 4 lamps on the column. It was very blue and not green at all. This was about 30 years ago. I vaguely remember asking someone at the time and he agreed that there were blue lamps and they meant something different to the red/amber/green on roads, but he wasn't sure what. The only reference I can find to blue lights on a google search are seperate ones indicating the edge of a tunnel etc, but not part of a "traffic light" set.
I've never seen that. What year are you referring to?
It's possible I'm remembering a switched off light. It was 30 years ago. But they were electric lamps - maybe they still used the same lenses? Maybe they had longer lasting yellowish filament bulbs? Road traffic lights at the time were green lenses, with I think a white bulb.
Railway signals in modern times have always had red, yellow (not amber) and green. A four-aspect signal has two yellows - the sequence approaching a stop signal goes G, YY, Y, R. There can be a number of other indications as well as the main signal but these are almost invariably white. There's a number of uses for blue and purple, but not appearing with the R/Y/G "traffic light" signals, at least in the UK. If you want to look at the full range of signs and signals,
Mike
I've never been fussy enough to even notice the difference between yellow, amber, orange. I could tell the difference if they were side by side, but I just think of a road traffic light as either yellow or orange. I couldn't even tell you what amber colour is compared to yellow and orange. I don't do things like "mauve", etc. Just purple, light purple, etc.
I assume this is to allow trains the longer stopping distance they require than road vehicles.
I might be thinking of non "traffic light" signals, or I might be thinking of a light which was off and was just seeing the blue lens which had a yellow light behind to make green.
That's a lot for a driver to remember! At least with road signs the symbol is meaningful.
I wonder why the red is at the bottom on rail lights and the top on traffic lights?
Well, when they used tungsten lamps, not many years ago. It may be just how the daylight caught the (unlit) lens.
Could be, never seen it myself, but then colour is subjective.
No, Blue was never part of railway standard signals. I am very hazy but ISTR two amber - sequnec being green-two amer - one amber - red as the obstruction was approached..
ISTR blue was something one saw on te railways but it wasn't part of the standard signals
Yes I think that is where the confusion came from actually. So many people have colour blindness that blue is normally avoided.
Brian
Not blue as such but the London Underground surgace lines used to use a bluish white light for fog signals athough it really was violet rather than blue.
The row of white lights which appear above a normal signal to indicate that the route is set for a junction can sometimes appear to have a slight bluish tint as can the flashing white light which indicates that it is safe to proceed across a level crossing.
No actual blue signals, though.
It's nowt to do with cycling anyhow. (xpost dropped)
People with colour blindness shouldn't drive trains (or cars for that matter).
And it's not very many, in fact I know of only one person who's colourblind.
Yes it was probably a light for something else I saw. Google refers to it being used for tunnels etc. Mainly for markers to show where an edge is (not sure why a train needs to know that, after all they can't be steered....)
It matter for railways due to needing to determine the colour from a long distance, due to the long stopping distance of a train. It is fine for a colourblind person to drive a car, as the stopping distance is short enough for the driver to get close enough to determint the position of the light on traffic light.
Up to eight percent of men of North European decent are red-green colour blind.
SteveW
Not so. I can see a red light (or brake light) out of the corner of my eye and act immediately. A colour blind person cannot do that and will react later than me.
A small number. Let them walk.
Since when were Northern European men decent? :-)
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