Blue railway signals?

On 14/12/2018 00:47, Steve Walker wrote:
On 13/12/2018 23:12, Rod Speed wrote:


"Fred Johnson" wrote in message
news
On Thu, 13 Dec 2018 21:03:57 -0000, Mike Humphrey
wrote:

Fred Johnson wrote:

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?

Railway signals in modern times have always had red, yellow (not
amber)

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.

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.

I assume this is to allow trains the longer stopping distance they
require than road vehicles.

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.

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.

If you want to look
at the full range of signs and signals, http://www.railsigns.uk/ has a
very comprehensive guide.

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?

Basically because when there are two ways of doing
something, you can be sure someone will do it both ways.

I am sure that I remember reading that it was based upon upper-quadrant
semaphore signalling, where a raised signal was "off" (clear) and
horizontal one was "on" (danger). Although both upper and lower quadrant
signals were used in the UK, they were almost all UQ (except on GWR
lines) from the 1920s - with the advantage that broken cables or heavy
snow caused them to drop to danger rather than the clear of LQ ones.
They simply copied UQ practice, so the top was clear and the bottom danger.

Yebbut with semaphore signals the light is always in the same position.

--
Max Demian

On 14/12/2018 09:27, Rod Speed wrote:
Nightjar wrote
Fred Johnson wrote

I wonder why the red is at the bottom on rail lights and the top on
traffic lights?

On railways it is at the bottom so that there is no light shade below
it, on which snow could build up and obscure the light.

So why didn't that continue with street lights ?

Perhaps the American who invented them hadn't thought about that
problem. Overground railway light signals were not standardised until
rather later - in 1924.

--
--

Colin Bignell

On 13/12/2018 16:42, Fred Johnson wrote:
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?

I have found a reference to an historic use of purple lights to indicate
there is a track circuit, which is a system to detect the presence of a
train.

--
--

Colin Bignell

On 14/12/2018 11:33, Nightjar wrote:
On 14/12/2018 09:27, Rod Speed wrote:
Nightjar wrote
Fred Johnson wrote

I wonder why the red is at the bottom on rail lights and the top on
traffic lights?

On railways it is at the bottom so that there is no light shade below
it, on which snow could build up and obscure the light.

So why didn't that continue with street lights ?

Perhaps the American who invented them hadn't thought about that
problem. Overground railway light signals were not standardised until
rather later - in 1924.

I have never seen a set of road traffic lights obscured by built-up
snow, not even during the worst of UK blizzards. Has anyone else?

In article ,
says...

Can anybody else remember blue traffic lights on railways?

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.

--

Terry

---
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On Fri, 14 Dec 2018 11:22:05 +0000, Max Demian, an especially stupid,
notorious, troll-feeding, senile idiot, blathered

And with whether hot and cold taps have the
hot one on the right of the pair or the left.

Usually hot is on the left.

LOL I've warned you senile idiots: after a few posts you all start sounding
as idiotic and ridiculous as the ****ed up Scottish ****** that you keep
feeding!

On Fri, 14 Dec 2018 09:14:06 +0000, Nightjar, another brain dead,
troll-feeding, senile idiot, driveled:


On railways it is at the bottom so that there is no light shade below
it, on which snow could build up and obscure the light.

Source ...other than your senile brain, troll-feeding senile idiot?

On Fri, 14 Dec 2018 11:44:49 +0000, Nightjar, another brain dead,
troll-feeding, senile idiot, driveled again:


I have found a reference to an historic use of purple lights to indicate
there is a track circuit, which is a system to detect the presence of a
train.

Are you two idiots planning on driving trains or what? Or are you simple
babbling away idiotically again because you got no one else in real life to
babble with? VBG

On Fri, 14 Dec 2018 15:12:11 -0000, Terry Casey, another mentally
challenged, troll-feeding, senile idiot, blathered:


No actual blue signals, though.

Just a load of useless inane troll fodder though, eh, troll-feeding senile
idiot?

On Fri, 14 Dec 2018 11:22:05 -0000, Max Demian wrote:

On 14/12/2018 00:20, Fred Johnson wrote:
On Thu, 13 Dec 2018 23:43:41 -0000, Rod Speed
wrote:
"Fred Johnson" wrote in message
news On Thu, 13 Dec 2018 23:12:50 -0000, Rod Speed
wrote:

Basically because when there are two ways of doing
something, you can be sure someone will do it both ways.

Like my bloody French car which has the wiper switch going down to
increase speed.

And with light and power switches in houses etc.

Down should always be on (except two or more way switches of course).

USA

It's down for on in the UK in almost every switch I've seen.

And then some bugger shows up who decides to do
them sideways so there is no confusion at all, and we
end up with 4 different ways of doing it instead of just 2.

Never seen a sideways lightswitch in a house.

Japan

Because they're too short to reach high enough to reach one that goes up?

And with whether hot and cold taps have the
hot one on the right of the pair or the left.

Usually hot is on the left.

Seems to be that way on all my sinks, but I'd say in other people's houses I see it the other way round in about 20% of cases. When I were a lad, the bathroom sink was definitely the other way round, can't remember the kitchen sink.