-
Our new ticketing site is now live! Using either this or the original site (both powered by TrainSplit) helps support the running of the forum with every ticket purchase! Find out more and ask any questions/give us feedback in this thread!
LED signals vs normal Colour Light Signals.
- Thread starter Voltage
- Start date
- Status
Sponsor Post - registered members do not see these adverts; click here to register, or click here to log in
R
RailUK Forums
O L Leigh
Established Member
On a point of pedantry, that's a 4 aspect head you're talking about. It may only have 2 lenses, but it can show all 4 aspects. A true 2 aspect head can only show 2 aspects; either red/green or red/yellow for a distant or related signal.
This isn't a new phenomenon, as the old "searchlight" signals with 2 lenses could still show all 4 aspects, so could we please get our definitions straight. The number of lenses that a signal head has does not define how many aspects it can show.
O L Leigh
Last edited:
90019
Established Member
Edinburgh Waverley is completely 2 lens, 4 aspect LED signals AFAIK, although I think there may be a couple that aren't on the eastern side of the station.
SuperVoyager
Member
There are a few 2 Aspect LED Signals down here on the approach to plymouth.
and on Plymouth platform 6 down signal
SuperVoyager
Member
True
O L Leigh
Established Member
2 lens, 4 aspect...?
O L Leigh
O L Leigh
SuperVoyager
Member
Yeah
FusionRail
Member
Put it this way, ive got a signal sat here, and the Pivot (shows red or white) has seperate LEDs for each colour. The white ones have a yellow patch inside, and the red are clear. So therefore, one can assume there are different LEDs for each colour. You can get tri-colour LEDs, but they are expensive, so for cost cutting we most likely use single colour LEDs. Then again it depends on manufacturer etc.
devon_metro
Established Member
Its quite obvious that they use multiple LEDs to display three aspects.
Notice the gaps between the lines of LEDs, if they were tricolour then the whole lens would light up with required colour.
Notice the gaps between the lines of LEDs, if they were tricolour then the whole lens would light up with required colour.
AlexS
Established Member
And at any rate for cost saving purposes you'll never get a 2 lens 2 aspect LED head because it defeats the cost saving object by virtue of being unnecessary.
Semaphore signals are very, very susceptible to 'feathering' and are at their best when the arm is against a patch of sky when you are approaching. I don't know if anyone has ever tried putting LEDs rather than a standard lamp in a semaphore to improve night visibility though!
O L Leigh
Established Member
Then it's a 4 aspect signal, not a 2 aspect signal.
O L Leigh
typical driver *shakes head* haha, i'm sorry
ungreat
Member
- Joined
- 11 Nov 2006
- Messages
- 964
Aspect means what its capable of,not how many lenses it has! Therefore a two lens signal of the LED type is capable of showing all four aspects..red ,1 yellow,2 yellows,green.
We have some on the approach to Peterborough from the south and KX approach too
--- old post above --- --- new post below ---
Typical driver?..now I know you are jesting but some arent...Theres a lot of armchair knowalls on here that really know nothing..Im not being offensive but the amount of wrong info is staggering!! Not this thread but just in general.
I know its hard sometimes to get facts but you only have to ask staff on here!!
We have some on the approach to Peterborough from the south and KX approach too
--- old post above --- --- new post below ---
Typical driver?..now I know you are jesting but some arent...Theres a lot of armchair knowalls on here that really know nothing..Im not being offensive but the amount of wrong info is staggering!! Not this thread but just in general.
I know its hard sometimes to get facts but you only have to ask staff on here!!
calm down it was just a simple error, what I meant was understood was it not. We all make mistakes.
And yes I am joking, I wouldn't say I know everything but I am rail staff lets be fair all rail staff share banter... part of the job!
There's several advantages of the LED signals:
1- Brighter -only 0.13% of electrical power on traditional signals is converted to useful optical light on the red aspect. 30% of electrical power is converted on LED types.
2- Multi-unit types with traditional bulbs, you can get 'phantom' aspects. This is why the insides are painted black.
3. Less maintenance. LEDs have much, much longer lives than SL35 bulbs - which are 12v/24W and have two filaments. Once one of the filaments goes, the S&T have to go out and replace the bulb, the service life is measured in weeks, whereas the LED units last 8 years. The signal lenses themselves are two glass prisms and the back of which needs to be kept clean. LED type signals are sealed units.
4. Predictable colours to BS1376. (railway signalling colours).
As a sub note the 4 aspect signal was invented in 1921 (and adopted in 1924), after a paper was submitted to the IRSE by AE Tattersall, the LNER's principle signalling engineer (also the the father of the modern power signalbox). The aspects relate to the indications not the number of light apertures. The early LNER 4 aspect signals were in fact insomuch they had 2 light apertures, but for the one light, an electro mechanical caddy was employed to rotate the lamps - not that reliable and required more maintenance. Which was why after 1960 multi-unit types became the norm.
4 aspect signals were first employed on the Southern region, and the ECML had a number automatic colour light sections from the 1920s/30s.
1- Brighter -only 0.13% of electrical power on traditional signals is converted to useful optical light on the red aspect. 30% of electrical power is converted on LED types.
2- Multi-unit types with traditional bulbs, you can get 'phantom' aspects. This is why the insides are painted black.
3. Less maintenance. LEDs have much, much longer lives than SL35 bulbs - which are 12v/24W and have two filaments. Once one of the filaments goes, the S&T have to go out and replace the bulb, the service life is measured in weeks, whereas the LED units last 8 years. The signal lenses themselves are two glass prisms and the back of which needs to be kept clean. LED type signals are sealed units.
4. Predictable colours to BS1376. (railway signalling colours).
As a sub note the 4 aspect signal was invented in 1921 (and adopted in 1924), after a paper was submitted to the IRSE by AE Tattersall, the LNER's principle signalling engineer (also the the father of the modern power signalbox). The aspects relate to the indications not the number of light apertures. The early LNER 4 aspect signals were in fact insomuch they had 2 light apertures, but for the one light, an electro mechanical caddy was employed to rotate the lamps - not that reliable and required more maintenance. Which was why after 1960 multi-unit types became the norm.
4 aspect signals were first employed on the Southern region, and the ECML had a number automatic colour light sections from the 1920s/30s.
We manage with traffic signals; the supply voltage is dropped from 230v to 160v via photocell.
Juniper Driver
Established Member
Down at Basingstoke and Southampton have ahem 2 lens 4 aspect signals.
I was actually thinking of building my own 4 aspect with the help of relays but haven't got round to how to do the circuit yet.
I was actually thinking of building my own 4 aspect with the help of relays but haven't got round to how to do the circuit yet.
Broken Viking
On Moderation
Just my t'pennys worth here... 
The whole of the Basingstoke ML between Basingstoke and Woking (And possibly as far up as Clapham) has recently had a lot of new gantries installed with LED signalling fitted, and from what I've been able to see they all have two "apertures" on them.
I don't know if the new LED signals down here are "live" yet, but their better sighting distances should hopefully give us a few extra mph in operational speeds, and every little helps IMO!
The whole BSML (As far as my limited knowlege goes) uses four-aspect throughout, and - Like others have mentioned above - One of those apertures will normally be capable of displaying three colours/aspects, with the second aperture showing amber only...Used to show a double-amber aspect, which isn't possible with a single fitting (Unless of course a fourth color is used.)
I know that blue is used in one or two places for special rules, and that orange is reserved for hi-vis use (Especially as orange would be too non-destinct from yellow and red) but couldn't they have used purple or another colour for the fourth aspect insted of installing a second lamp in each signal?
On the bright side though: It just hit me that the new LED signals could each carry two three-aspect lamps in them, which could offer five-aspect and higher signalling to be had everywhere at very little cost. Five aspect on the BSML would be handy in itself (Allowing up to 225mph operation) but having that on the WCML would be a Godsend for us speed-freaks! 8)
Indeed...That's a very interesting proposition! Eliminating all possible aspects involving red (Which must always be taken as danger) gives us two colours per lamp (Amber and Green), each of which may have two presentational aspects (Steady or flashing). Putting this all together gives us ((2 colours x 2 presentations) x 2 arrays) = (2x2)x2) = Potential for 8-aspect signalling...And if ye add blue LEDs to the signal heads as well, that turns into (3x2)x2 possible combinations, or a whopping 12-aspect system!
hock:
Just imagine what kind of speeds we'd be allowed to thrash to with that degree of control in the signalling system, eh?hock:
>> Death <<
The whole of the Basingstoke ML between Basingstoke and Woking (And possibly as far up as Clapham) has recently had a lot of new gantries installed with LED signalling fitted, and from what I've been able to see they all have two "apertures" on them.
I don't know if the new LED signals down here are "live" yet, but their better sighting distances should hopefully give us a few extra mph in operational speeds, and every little helps IMO!
The whole BSML (As far as my limited knowlege goes) uses four-aspect throughout, and - Like others have mentioned above - One of those apertures will normally be capable of displaying three colours/aspects, with the second aperture showing amber only...Used to show a double-amber aspect, which isn't possible with a single fitting (Unless of course a fourth color is used.)
I know that blue is used in one or two places for special rules, and that orange is reserved for hi-vis use (Especially as orange would be too non-destinct from yellow and red) but couldn't they have used purple or another colour for the fourth aspect insted of installing a second lamp in each signal?
On the bright side though: It just hit me that the new LED signals could each carry two three-aspect lamps in them, which could offer five-aspect and higher signalling to be had everywhere at very little cost. Five aspect on the BSML would be handy in itself (Allowing up to 225mph operation) but having that on the WCML would be a Godsend for us speed-freaks! 8)
Indeed...That's a very interesting proposition! Eliminating all possible aspects involving red (Which must always be taken as danger) gives us two colours per lamp (Amber and Green), each of which may have two presentational aspects (Steady or flashing). Putting this all together gives us ((2 colours x 2 presentations) x 2 arrays) = (2x2)x2) = Potential for 8-aspect signalling...And if ye add blue LEDs to the signal heads as well, that turns into (3x2)x2 possible combinations, or a whopping 12-aspect system!
hock:Just imagine what kind of speeds we'd be allowed to thrash to with that degree of control in the signalling system, eh?
hock:>> Death <<
O L Leigh
Established Member
We've had this discussion before.
Without going over ground already well-trod, the brightness of an LED signal does not improve the sighting. There has to be a certain amount of time for a driver to see, identify and correctly respond to a signal aspect. Adding extra aspects with lots of wonderful colours will just be too much complication.
As I've said before, fixed lineside signalling equipment is only good for a maximum of 125mph. If you want to go faster than this you absolutely have to have in-cab signalling. Dreaming up new signal aspects to pad it out from 4 aspects to however many you can work out won't achieve this.
O L Leigh
Without going over ground already well-trod, the brightness of an LED signal does not improve the sighting. There has to be a certain amount of time for a driver to see, identify and correctly respond to a signal aspect. Adding extra aspects with lots of wonderful colours will just be too much complication.
As I've said before, fixed lineside signalling equipment is only good for a maximum of 125mph. If you want to go faster than this you absolutely have to have in-cab signalling. Dreaming up new signal aspects to pad it out from 4 aspects to however many you can work out won't achieve this.
O L Leigh
FusionRail
Member
Plus it would be way too confusing for drivers. Also, all the signalling equipment would have to be replaced/upgraded, more signals added to cope with the extra aspects going to Danger, so therefore it would be a complete waste of time and money!
robvulpes
Member
- Joined
- 11 Jan 2007
- Messages
- 172
Just my t'pennys worth here...
The whole of the Basingstoke ML between Basingstoke and Woking (And possibly as far up as Clapham) has recently had a lot of new gantries installed with LED signalling fitted, and from what I've been able to see they all have two "apertures" on them.
>> Death <<
No - the north-eastern limit of LED signals will be between Farnborough and Brookwood, where the Basingstoke signalling area ends. Pirbright Jcn -> Brookwood -> Woking -> somewhere on the London side of Surbiton was resignalled only a few years ago with 4 aspect 'traditional bulb' signals (controlled from Woking).
When I last went that way in late Feb, the new signals hadn't yet been commissioned in the Farnborough area, but that may have happened since.
(Will find out on BH Monday en route to the Eastleigh 'do')
Rob
Ive always been intrigued by this magical 125mph limit "due to signalling".
What studies have been done on this to ascertain at just what speed it becomes less safe for drivers to respond to signals? Or was it just a convenient limit applied due to the HST et al?
What studies have been done on this to ascertain at just what speed it becomes less safe for drivers to respond to signals? Or was it just a convenient limit applied due to the HST et al?
O L Leigh
Established Member
It's partly to do with the length of a signal section. When 140mph running was trialled on the ECML it was necessary to introduce a 5th aspect (flashing green) to permit this enhanced speed because it would take a train that much longer to stop from 140mph than from 125mph. Consequently the 5th aspect inserted an additional signal section between unrestricted running and the red to give trains that extra room to stop.
But mostly it's to do with the amount of time that a fixed lineside signal will be visible by the driver at higher speeds. The higher speeds mean that there is less time for a driver to see and correctly identify the signal for the line the train is travelling on, register the aspect being shown and react to it. This might not seem like a big problem, but imagine what it's like when it's dark or foggy or raining hard or the driver is coming to the end of his/her turn of duty and is tired.
O L Leigh
But mostly it's to do with the amount of time that a fixed lineside signal will be visible by the driver at higher speeds. The higher speeds mean that there is less time for a driver to see and correctly identify the signal for the line the train is travelling on, register the aspect being shown and react to it. This might not seem like a big problem, but imagine what it's like when it's dark or foggy or raining hard or the driver is coming to the end of his/her turn of duty and is tired.
O L Leigh
And at any rate for cost saving purposes you'll never get a 2 lens 2 aspect LED head because it defeats the cost saving object by virtue of being unnecessary.
Semaphore signals are very, very susceptible to 'feathering' and are at their best when the arm is against a patch of sky when you are approaching. I don't know if anyone has ever tried putting LEDs rather than a standard lamp in a semaphore to improve night visibility though!
Some semaphores have had LED installed I belive Tram Inn box has some on the Marches
Yank 119
Member
Relevant to the discussion, have a look at this nice HD video of the ECML near PBO, complete with LED signals AND the flashing fifth aspect.
http://www.youtube.com/watch?v=LDQxqXorWDk
http://www.youtube.com/watch?v=LDQxqXorWDk
Aussie_Rail
Member
They've been replacing the old signal lights with these new LED lights for a little while in Victoria, my only problem is they are so bright! You can spot them off from a mile.
I've heared of some train drivers here wearing sunglasses at night because they are so bright.
They've been doing that with traffic lights as well, although there are so many more lights to do though. Do you guys also have traffic lights fitted with LED's?
I've heared of some train drivers here wearing sunglasses at night because they are so bright.
They've been doing that with traffic lights as well, although there are so many more lights to do though. Do you guys also have traffic lights fitted with LED's?
Yes, I guess they've been used for around 5-10 years - normal bulbs are still by far the majority though. Continental European countries are also using LEDs.
- Status