Gw electrification - where can I get a summary of plans?

[whole diary]

[TonyK]

All signal heads are replaced with LEDs ASAP. That's nothing to do with the planned resignalling, but it frees up the effort that has to go round checking and replacing bulbs.

Does this mean the end of the 2/3/4 lens signal in favour of a single aspect with variable colour LEDs?

[John R]

Indeed it will, eventually. I noticed some have sprouted between Chippenham and Wootton Bassett Jn very recently and are still covered over.  I would imagine it will take a fair while to cover the whole country though.

And note that four aspect signals still need two lens.

[TonyK]

Indeed it will, eventually. I noticed some have sprouted between Chippenham and Wootton Bassett Jn very recently and are still covered over.  I would imagine it will take a fair while to cover the whole country though.

And note that four aspect signals still need two lens.

Noted, although not fully understood...

[John R]

Given one of the aspects is a double yellow, two lens are needed to display it, with a suitable space in between so that from a distance the separation is clear and thus distinct from a single yellow. 

[JayMac]

An example:



Showing double yellow or (preliminary caution) as described by John R. Bottom lens also usually displays red (danger, stop), single yellow (caution) or green (proceed). Top lens usually displays yellow only as part of the double yellow aspect, although any aspect configuration can be achieved with appropriate wiring and LEDs, particularly for emergency back-up purposes. For example, if the bottom lens fails the top lens could be configured to still work as a three aspect signal. Although prolonged use of the top lens to display a red aspect is to be avoided, both for driver sighting reasons and the potential for the top lens to be blocked in winter by a build up of snow on the lower lens cowl. Although this is less likely with the spacing between the lenses.

[stuving]

There's a lot of these LED signals at Reading, though it is hard to see what the aspects fitted really are (I've certainly never felt inclined to wait for them all to show). For example, the ones with just a tricolour "searchlight" (e.g. platform starters) have a blank second aspect.

Do you remember those signal and track diagrams from Easter 2013? (See http://www.firstgreatwestern.info/coffeeshop/index.php?topic=6405.820.) They do indicate what the signals can show (though now a little out of date). However, some of those diagrams are a bit puzzling. For example, old pre-rebuild signals still with all four aspects, but drawn with what was the red as a tricolour. Or new ones with a tricolour, yellow, and green. I'm sure it all makes sense, if you know why.

[eightf48544]

The heads of these new LED signals come in basically 3 standard boxes, single tricolour, 4 aspect as shown and either single tricolour or 4 aspect with juntion indicators. Hence the ones you see at Reading with 4th aspect balnk.

The signal diagrams for drivers are being updated regularly as work progresses.

[TonyK]

Given one of the aspects is a double yellow, two lens are needed to display it, with a suitable space in between so that from a distance the separation is clear and thus distinct from a single yellow. 

Figured it out for myself on the wary to bed. I can be a bit thick at times.