Types of signalling

Looks like someone listing the signal control systems in use on the Underground.

There are a couple or more signalling experts on here, I'm sure one will be along to assist.

However, our very own harsig has his own website that might be of some help to you: Clickety Click

Meantime, hang tight, someone will know the answers.

There is also Edgware Road, which is a B style frame.



The only ones that contain N2 frames of this type, to my knowledge, are Ealing Broadway and West Kensington East.









Plus the Victoria Line, whose Westrace interlockings are currently in read-only mode on top of the existing V frame IMRs.

1. Manual 'N' - a signalman hand operating miniature levers. (signalman in a cabin with the frame)
2. Converted 'N' known as 'N2' such as Ealing Broadway (an IMR site) operated by PMCs at EBY and regulated by signal operators (used to be regulators) at Earls Court.
3. An IMR with a 'V' style frame and signal man somewhere else controlling it with a push button panel (Farringdon/Aldgate used to be like this). (two regulators/signalmen in Farringdon signal cabin each with a PB panel, one working Aldgate Area and the other the Farringdon area with IMRs at Aldgate, Moorgate and Farringdon.
4. much the same as 2. IMRs with 'V' style frames such as Northfields and Boston Manor operated with PMCs and regulated by signal operators at Earls Court.
5. There are no frames on the Central or the JLE so relay interlocking must apply to both, I know the JLE uses PLCs and ladder logic but I've never seen or worked on it.
6. Westrace is also something I know nothing about as it wasn't used on the lines that I worked as a signal maintenance TO. However, my understanding is that it is a control system that is simply another way of remote controlling signalling.

Whether lever frames are used or not and what type is not particularly relevant or irrelevant to any line as such, whichever system is used there is interlocking at each level and each level is one building block in a system, that system can be manual, automatic, programmed, timetabled, computerised, locally or remotely controlled and fully interlocked using the different building blocks to create such an interlocking that might be used anywhere.
The lowest level of interlocking is mechanical at trackside but there can be mechanical, electrical and/or electronic locking at any level as suited to the technology and equipment in use. Over the years LT/LU has mixed and matched technologies to create systems which apply the same safety signalling principles but wherein every site is unique to a greater or lesser extent. It is thus difficult to pin down any one system to any given line as whatever was current thinking at the time became the 'system' and there has never been a single standard applied to all sites on all lines, nor could there be for all sorts of reasons that aren't relevant in this thread.
Current thinking is to do away with lever frames altogether and LU is perhaps somewhat unique in the modern railway world as it still has so many.

Thanks Tom, all stuff that I have never seen. Hands up on the Westrace which I did believe to be more of a remote control system i.e. my thinking was of it being almost entirely non-safety. I admit to finding it difficult to draw a line between safety and non-safety where there are no lever frames and where I have never seen the equipment!
I'm not sure what happened at T5, one of my former colleagues left Tube Lines and was doing the installation work there just before I retired. My recollection was that the old T123 computers were going to be replaced with something new,I presume new computers but I don't know.