IRSE Exam Forum

Full Version: British Power Signalling
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
For all you are likely to want to know about the different forms of signalling panels, powerframes etc, well illustrated with lots of example photographs
(15-10-2010, 11:04 PM)PJW Wrote: [ -> ]For all you are likely to want to know about the different forms of signalling panels, powerframes etc, well illustrated with lots of example photographs

Interesting stuff, well at least for me from outside the signalling world.

An equally interesting general read document about LU V frames (remote controlled power frames)

Way outside my area of work but useful to know the terminology to pretend to understand what LU SOMs and TOs are on about sometimes.


Hi where can i find more detailed info. about the British signaling. What actually is signaling and how many types of designs are there in all?
(29-10-2011, 07:27 AM)alexnikol Wrote: [ -> ]Hi where can i find more detailed info. about the British signaling. What actually is signaling and how many types of designs are there in all?

Depends what you are after; there are quite a large number of commercially published books.
"Two Centuries of Railway Signalling" by Geoffrey Kitchenside and Alan Williams ISBN 978-0-86093-618-3 is certainly good coverage (probably it is 75% UK content, with 25% elsewhere).

However if you are only interested with relatively current UK practice then Stanley Hall's little book in the Ian Allan series is compact and much cheaper. My copy is called BR Signalling Handbook ISBN 0-7110-2052-3 but this has been republished rather more recently and called I believe Modern Signalling Handbook, but content very similar so I didn't spend my money.

These books are for the interested amateur so are easy to read and are not definitive, but they are accurate.

Not sure how to answer your question "WHAT IS SIGNALLING?" this could acually be a 30mins exam question!
The essence of it must be communication to the driver so that the movements of all trains are co-ordinated in a manner that ensures:
a) the railway is safe,
b) the traffic can be routed and perform the required operational moves (joining, splitting, shunting etc)
c) the traffic flows effectively and efficiently,
d) good journey times
e) adequate capacity on the network
f) minimum use of resources (infrastructure, energy, labour).

Therefore anything that plays a part in the above is partof a signalling system, but what is suitable depends upon the context. At one extreme there may be very little technology with communication being by flags; at the other extreme there may be no signaller or driver and the entire ralway could be automated, Generally though the signalling system lies somewhere between these extremes, but in the UK this might be
1) mechanical signalling with no train detection other than the human and no train protection, or
2) colour lights with continuous train detection and limited train protection or an in-cab display, or
3) trains reporting their own position and comprehensive train protection.

How many designs?
Well every site is unique in its application.......
Indeed even in terms of "standard circuits" there has always been a gradual evolution so even on a single re-signalling programme there may be differences between the design standards used for the latter installations than were initially adopted, Each of the BR Regional design offices had their own way of doing things / interpreting what was supposed to be a common standard- some more than others! There have always been various competing contractors involved and each has their own range of equipment that naturally they prefer to use. Hence with many different strands, each of which evolves and with some inter-marrying, the "genes" have quite mixed up and so it is hard to say where one variety ends and another begins......

At a high level though I would consider
A. Semaphore signalling with mechanical interlocking and limited electrical controls
B. Modernised such installation where some or all of the signals are colour lights, largely track circuited, basic locking undertaken mechanically but with many electrical locks
C. Miniature relay frame with locking undertaken either mechanically or electrically, power operating (electricity or compressed air) the outside signals and points.
D. Small basic simple panel operating a form of relay interlocking that then operates the external equipment electrically; the panel might require the signaller to operate the points into relevant positions before attempting to clear the signal or the route may automatically call the points.
E. More extensive and complicated panel where the signaler selects route entrance signal and route exit signal (generally pushbuttons) and the route then sets calling points as needed. Comprehensive indications of route and track lights etc. Route relay interlocking either "free-wired" to one of several standards or using one of the varieties of "geographic" interlockings.
F. Functioanlly as per E but implemented by Solid State Interlocking with serial data link to the panel PMUX and also Trackside Data Links to the outside locations containing Trackside Functional Modules that then control the points and ignals electrically, often directly switched by the electronics.
G. As F but with the signallers interfaace being via a VDU screen which largely emulates the operation of a panel.
H. Similar but using some other more modern form of Computer Based Interlocking, probably also a different form of VDU display which may well be an application on a PC running Windows.
J. A signalling system broadly like H but where the communication is to aard the train driving an in-cab display for the driver, often utilising radio but possibly via coded track circuit or inductive loops laid in the track.

On that basis I make it 9 broad types but others might divide differently and could make either more or alternatively fewer. Many of these broad categories could easily be refined into 5-10 or even more sub-categories; hence you could get the number of types to be any number you wanted, but hopefully this gives you an idea.