Variety of signals

[Railsigns]

The incandescent bulb signals have the lights in a fixed position for the most part. There are/were some searchlight signals, however apart from those exceptions, a driver could glance at a signal and even if the colour wasn't perfectly discernable, if they could see a lamp in a certain position in the head was lit, then they would know what the aspect was.

That wouldn't work on any line where the signals aren't all of a uniform format, e.g. lines with consecutive pairs of two-aspect stop and distant signals. Nor would it help at night. It's a bold driver indeed who can't discern what colour is showing but claims to know from its position within the head alone.
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Am I right to say that LED signals stops that issue of wrong colour interpretation, meaning that it stops the chance of a driver getting a red confused for yellow. [?]

No, not entirely.

 

[edwin_m]

Exactly what he said.

The incandescent bulb signals have the lights in a fixed position for the most part. There are/were some searchlight signals, however apart from those exceptions, a driver could glance at a signal and even if the colour wasn't perfectly discernable, if they could see a lamp in a certain position in the head was lit, then they would know what the aspect was.

That may be clear, but I'm struggling to see how a train driver will be able to see that light is coming from a particular lamp out of three or four adjacent ones is lit without being able to tell what colour it is. I believe this is a reason for road traffic lights to have separate lenses, but while those with colour blindness can drive on the road, they are not permitted to drive trains.

 

[Cherry_Picker]

The problem a train driver has is that he/she needs to know what aspect a sign is displaying from a distance of hundreds of yards away while traveling at high speed, often in the dark. They can't rely on the position of the lamp for that information. The comparison to traffic lights is a poor one.

 

[455driver]

455driver, which of these three LED signals do you prefer (and you can't answer neither! )

In that case I refuse to answer!

I havent worked past any VMS signals so cant comment except to say that by what I have heard from the diseasel drivers from Salisbury they do seem to suffer from the same problems as the other LED signals. I am not familiar with some of the other signals either.
The head which uses the 3 aspect bottom aspect with the upper yellow aspect suffer from the fact that the aspects are too close together so from a distance can appear to be a single yellow instead of the double yellow actually displayed.
I am familiar with the one IrishDave has posted and they again are too bloomin bright but dont cut through fog.

The best are the conventional heads with the lamps replaced by an LED pack and retaining the glass lenses on the front to focus the beam. I think I have got some pictures somewhere and will dig them out over the weekend.
The only thing different from our point of view is the colours are more vivid (which is a good thing) and I do like them a lot.

I can understand why they are going for LEDs (and they are good reasons) but they need to listen to the drivers for a change and deal with the issues, for one thing brighter isnt always better!

I would like to see a study done into signals visibility in various conditions and which signals are best when using the mark one eyeball rather than some fancy testing equipment.

 

[rebmcr]

Thats fair enough but it could have been explained a tad bit better. In my mind saying "position-light" in a thread about signals can refer to something else.

That's actually the real technical name for it.

The problem a train driver has is that he/she needs to know what aspect a sign is displaying from a distance of hundreds of yards away while traveling at high speed, often in the dark. They can't rely on the position of the lamp for that information. The comparison to traffic lights is a poor one.

Very well!

 

[507 001]

We have one Dorman LED signal on metrolink (signal 50 at Victoria) and it's bloody awful. It's ground mounted but still manages to perform laser eye surgery on you every time you drive past!

 

[tomi_robo]

There is in fact a fourth type of LED signal, but I've only seen it on the Chiltern main line thus far: it's got separate heads for each aspect, just like a signal with incandescent bulbs. See this picture: http://www.meadwaypark.co.uk/ChilternGX/Edit%2006018.jpg at Gerrards Cross. Not sure who they're made by.

This is Signal House, there are a lot of these on the Chilterns.
http://http://www.collis.co.uk/signal-house

 

[LowLevel]

There's similar signals elsewhere - near Manchester (I think) and also two signal heads near Alfreton? that are LEDs but with seperate LED units for each aspect. They don't really seem to have caught on especially with the new light engines in traditional colour light heads.