identifying signals

[tube10]

How can I tell if the signal is an interlocking or a block signal on the underground?

[Deleted]

If I've understood the question correctly, block signals have the preface "A" on their plate, all other signals have a different set of two or more letters... but then I'm stationside, what do I know? ;)

[signalfailure]

I thought if the signal has A or X in the plate that means its an Automatic Sig?

[mrfs42]

I would heartily recommend that you read tubeprune's excellent pages on signalling - you'll find out where NU is for a start.

Then you'll get onto J.... M...... T....... FNX....... EE. EC. EI. OB. OD. OH. ET. LL. LZ.

I think <from memory> you'll find a comprehensive listing and explanation on the semi automatic signalling page.

A or S means that it is an Auto - <diddleum diddleum> X means it is the last Auto before an interlocking (unless it's a signal protecting a floodgate or possession)

If I understand the question correctly, given your location it is feasible to say that all signals on LU are block signals - some are permanently 'fleeted' - i.e. A or S all others are block signals capable of fleeting but are block signals for (predominantly) remotely controlled interlockings.

(I hope you see what I mean - it is a long, long time since I've looked at 'fleeting', 'non-stick', 'semi- stick' and TORR circuits)

<much later edit>: never a good idea to try and harmonise LU and NORAC signalling terms source of much puzzlement - I've now got all sorts of ancient signalling textbooks spread over the library!

[Deleted]

also just to add PNX signals are ones that would protect a possession
FDX are ones to protect a floodgate

[Deleted]

aetearlscourt said:

FDX are ones to protect a floodgate

The numbering of floodgate signals varies from line to line, so FDX would be on the District, FNX on the Northern etc. Also whilst a "regular" X signal (the last automatic before entering a controlled area) would normally be numbered with the cabin code of the area plus X, in some places it is just X then the track circuit number with no cabin code.

tfc