LED signals vs normal Colour Light Signals.

[Voltage]

In the Basingstoke area and the Up line between Basingstoke and Woking, LED signals are being introduced to replace the standard 3/4 aspect signals.

The LED signals look like normal 2 aspect signals, but the bottom lens can display a red, yellow or green aspect. The top lens is for double yellow aspects in the case of 4 aspect signalling.

I prefer the look of a normal 3 or 4 aspect signal, though I understand LED signals are brighter. Just wondered what everyone else preferred.

 

[90019]

Personally, I prefer the LED signals.
Although I prefer LED light clusters on most things

 

[EE Type 3]

Aslong as the signals work, I don't really mind

Although given the choice, can't beat a peg or two. Good job I live in semaphore heaven then :razz:

 

[O L Leigh]

The new 4 aspect LED signalhead arrangement is identical to the old 4 aspect searchlight signals and are absolutely fine. From an operational perspective they are bright (almost too bright), the colour definition is very good, they use less energy and the LED heads will last longer than the old fashioned filament bulbs.

Unfortunately aesthetics never really entered into the design and construction of infrastructure. *Sigh*

O L Leigh

 

[Voltage]

The new 4 aspect LED signalhead arrangement is identical to the old 4 aspect searchlight signals and are absolutely fine. From an operational perspective they are bright (almost too bright), the colour definition is very good, they use less energy and the LED heads will last longer than the old fashioned filament bulbs.

Unfortunately aesthetics never really entered into the design and construction of infrastructure. *Sigh*

O L Leigh

I agree with you about the brightness of the LED signals. At Basingstoke when my starting signal was showing Danger, the red aspect is blindingly bright when viewed from the cab. This was during daylight. I can't imagine the brightness of them at night. Im a new train driver so haven't had the chance to drive at night yet (though have rode in the cab during darkness)

 

[O L Leigh]

We've got a couple of related signals inside the airport tunnel at Stansted. The "Up" signal is an LED while the "Down" is the older colour light type with a filament bulb. You can really tell the difference in the dark.

The only downside of the LED's is that they are very directional. If you pull right up close to one you tend to lose the aspect and see the signal as a dark chequerboard. However, there is a "fringe" that repeats the aspect using a different type of LED that is less directional. You can get an idea of it from this pic I took of L54 signal at Liv St.

BTW, welcome to the forum. It's always good to have railstaff onboard.

O L Leigh

 

[Voltage]

We've got a couple of related signals inside the airport tunnel at Stansted. The "Up" signal is an LED while the "Down" is the older colour light type with a filament bulb. You can really tell the difference in the dark.

The only downside of the LED's is that they are very directional. If you pull right up close to one you tend to lose the aspect and see the signal as a dark chequerboard. However, there is a "fringe" that repeats the aspect using a different type of LED that is less directional. You can get an idea of it from this pic I took of L54 signal at Liv St.

BTW, welcome to the forum. It's always good to have railstaff onboard.

O L Leigh

Yea I know what you mean about the 'Fringe'. When standing on the platform at Basingstoke some time ago I looked closely at an LED signal showing Danger and could see this 'halo' around it. Thanks for the welcome. Im quite into signals as well as trains

 

[O L Leigh]

Here's the full resolution close-up for those who are interested.

 

[MCR247]

Although I prefer LED light clusters on most things

Especially 170s, but than the old light clusters we get around here (ex MML, CT) apart from 397/398!
Also 377s. Dont like the 1st half of /1s or /3s. Would go into detail on the 375s, but I dont want to bore everyone when I dont know anhything about them! :roll:

 

[me123]

I've heard some staff (I think on here) saying that, as you get closer to the LEDs, you're no longer able to see them for some reason (I think it depends on where they're positioned). Is this true, and if so what impact does it have on driving the trains?

 

[O L Leigh]

See my posts above.

O L Leigh

 

[me123]

Did read that, obviously I didn't read it if you know what I mean

 

[O L Leigh]

No problems.

**EDIT**

Whoa...!! I've got to stop looking too closely at my pics. Am going to replicate this in the quiz section.

O L Leigh

 

[90019]

you're no longer able to see them for some reason (I think it depends on where they're positioned).

Its to do with how the light is emitted from the LEDs; some only emit light directly out the front, whereas some, the light is visible at up tp 90 degrees to the LED itself, it varies depending on the LED used (Although I cant remember exactly what it is that's used to control the angle at which the light is visible). From what i can tell the ones used in signal are visible probably up to about 45 degrees or so, judging on the comments about not being able to see them if you're too close.
The obvious solution would be to have some LEDs angled within or on the edge of the light cluster, increasing the light's overall visibility from different angles.
--- old post above --- --- new post below ---
Actually, looking at the pic further up, it appears as if there are some angled LEDs on the edge of the cluster.

 

[FusionRail]

Well they are easier for us on the maintenence side, as obviously theres no filaments to keep changing, and there are more componentized. (Yes, they are termed filamants, not bulbs)

Also LED signals are smaller, more compact (as they can have multiple aspects on one LED cluster, instead of one aspect for each aspect so it generally looks tidier.

Some information: the filaments have two filaments, so when one goes the signals internal relay switches over to the second one, which is slightly dimmer.

 

[37401]

LED is good but so is Normal signals its a hard choice so im just gonna say semaphore

 

[Voltage]

Something I forgot to add the other day, theres a number of LED Banner repeater signals on the South West Trains network. I do prefer these to the older banner repeaters that just have a mechanical black bar inside a white circular case.

 

[dave55uk]

These 3 aspect LED signals, do they have seperate LEDs for each colour or are they tri-colour LEDs?

 

[vitesse]

LED ground position lights and main aspects are a lot easier to see during the day, far less prone to bleaching from sunlight. Blindingly bright at night though.

 

[Sir_Clagalot]

The LED heads are far too bright at night. Surely they could have been fitted with a LUX sensor that dimmed the output in such a way that the driver isnt blinded yet can still see the signal at the required distances.

 

[matchmaker]

These 3 aspect LED signals, do they have seperate LEDs for each colour or are they tri-colour LEDs?

Tri-colour

 

[FusionRail]

The LED heads are far too bright at night. Surely they could have been fitted with a LUX sensor that dimmed the output in such a way that the driver isnt blinded yet can still see the signal at the required distances.

LEDs dont dim easily, they are a diode, so they are either on or off.

 

[90019]

LEDs dont dim easily, they are a diode, so they are either on or off.

I'm sure there are ways to do it, but with tri colour diodes I think it'd be a bit more difficult, however one way you could do it is to have less of them on at once. Like having every 3rd one off in the line or something like that.

 

[me123]

The LED heads are far too bright at night. Surely they could have been fitted with a LUX sensor that dimmed the output in such a way that the driver isnt blinded yet can still see the signal at the required distances.

As Fusionrail's said, diodes can only be on or of. Therefore, an LDR or similar would just turn them off at night Not a good idea; I can imagine a rather large increase in SPADs.

Tri-colour

I'm sure it's different colours of LED; one row of Red, one of Yellow, one of Green, repeat. The reason I'm saying this is because when you're up close, you can see some black lines in them. Also, because the diode can only be on or off, I was under the impression that a tri-colour LED would have to show all three colours at one time; a railway full of yellow signals wouldn't be entirely useful. I'm open to correction on that one!

 

[westcoaster]

i believe there are three different colours in the signal head, also on the bit about the signal not being clear when you are up close, this also happens when you have the sun sitting low in the sky. As the head of the signal is like a lens of a pair of glasses, and not rippled like normal signal lenses. They can be very bright also especially a set of double yellows flashing (lights up the whole cab).

 

[90019]

Also, because the diode can only be on or off, I was under the impression that a tri-colour LED would have to show all three colours at one time; a railway full of yellow signals wouldn't be entirely useful. I'm open to correction on that one!

There's a way of doing it by having different inputs, if they are tri-colour, they'll have 2 or 3 input legs on each diode, depending on how it's done.

 

[me123]

So, effectively, it's 3LEDs in one bulb so to speak?

 

[90019]

So, effectively, it's 3LEDs in one bulb so to speak?

It can be done.
Although, I'd guess that they're done with only 2 inputs, one red, one green, and yellow is when they're both on. and a single output.

a1 - input for red
a2 - input for green
k - output

The only thing is the different voltages that they'll run at, although that's not a dificult problem to solve

 

[TDK]

LED is good but so is Normal signals its a hard choice so im just gonna say semaphore

I cover a lot of track driving and encounter LED 4 aspect (so to speak) LED 3 aspect (so to speak) 2, 3 & 4 aspect SL standard heads and semaphore my opinions are:

Semaphore - Useless and should all be replaced.
Standard SL heads - Good but are a problem in strong sunlight and not easy to pick out.
LED - by far the best although very bright. When close up the top left is easily visible. One thing I have noticed with the LED signals is that when the sun is shining directly on the signal and the aspect is not illuminated including junction indicators the glow white and this can be distracting and also on occasion make you need to change your underpants.

For you to say semaphore is the best I think you are not a driver.

 

[O L Leigh]

It may be feasible to have tri-color LED's, but mainline LED signal heads have rows of LED's arranged by colour. This is only really obvious when you get close up to one, but you can clearly in the pic below that there are rows of red LED's between which there are two rows of unlit LEDS.