Signals on the L&M

[ElectroSoldier]

Hey guys, I have a question about a signal on the L&M I hoped you can help me with.

 

I noticed this rather odd thing while watching a youtube vid, its a cabride from Manchester Victoria to Lime street.

 

 

The picture is made just after the train passes control signal HN15 on the Down Chat Moss line.
As you can see from the picture its a semaphore signal on a gantry protecting movement onto Up Chat Moss from the Down St Helens line at Huyton Junction.

 

I was wanting some more information about it if you have any like what is the controlling signal box? Is it the section signal of Down St Helens before the line passes to Huyton box, if not why is it semaphore...

Any more details at all would be great, as I only have what I can imagine looking at the lay of the track in the area.

 

Orignal video here, watch from 44:55

[LMS2968]

That signal is (was) HN11 and was Huyton's Down Inner Home off the St Helens Line, the Outer Home being HN17. The Chat Moss line went over to colour light some time ago, but the St Helens line retained semaphores.

[The Stationmaster]

You can in fact work it out - to some extent from the video - like this

 

1. The train halts at signal HN15 protecting the junction, therefore the semaphore signal protecting the junction on the other line will be worked by the same signalbox.

 

2. The semaphore signal is considerably less than any sort of Clearing Point distance from the junction is therefore most likely to be an Inner Home Signal (Home 2 in LMR parlance) - the normal Clearing Point for Absolute Block was 440 yards but back in the 1980s it was reduced to 200 yards where there is a colour light distant signal.   The signal appears to be too close for the junction than even that so it is most likely to be an Inner Home which would be at least at Clearing Point distance from the Home Signal which lies in rear of it.

 

3. The arrangement is rather unusual but was clearly done like that to save money in providing colour light signals on the St Helens Line.

 

LMS2968 has of course provided us with the full information but it's always interesting (to me at any rate) to observe and see what can be concluded from what we see in front of us - which I did before I got to LMS2968's post).

[Mike Bellamy]

Am I the only one who read the title and thought of the Leek and Manifold Railway - then got a great sense of disappointment to find that not only was it modern but was standard gauge as well . . . !

 

 

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[LMS2968]

Probably, Mike, yes. I'd say that THE L&MR has to be the historic Liverpool & Manchester Railway, the father of all others!

[The Stationmaster]

Probably, Mike, yes. I'd say that THE L&MR has to be the historic Liverpool & Manchester Railway, the father of all others!

Quite agree - I wondered if it was going to be about the spacing between Policemen or some other question about the early forms of signalling!

[ElectroSoldier]

That signal is (was) HN11 and was Huyton's Down Inner Home off the St Helens Line, the Outer Home being HN17. The Chat Moss line went over to colour light some time ago, but the St Helens line retained semaphores.

 

Does that make it an intermediate block home signal?

[LMS2968]

No. An Intermediate Block signal splits a long block into two shorter ones, but is controlled by a signal box at the outer end of one or other of the blocks, there being no box between the two sections. An Inner and Outer Home are both controlled by the same box. As Mike the Stationmaster says, there has to be a  distance beyond a Home signal, previously a quarter mile, which was clear of any obstruction before a train could be accepted into the section in rear. So if at the junction, a train using the other route had priority, either the train could not be accepted into the section or the signal had to be a quarter mile back from the junction. By using Inner and Outer Homes, the train could be admitted up to the Outer Home. Once the train has been brought "nearly to a stand", the outer Home can be cleared and the train brought forward as far as the Inner Home still at Danger, until the junction is clear and that signal can be lowered. This saves some distance and therefore time.

[ElectroSoldier]

I see now.

So the signal in the rear of that one is at least 440 yards away and is, or could be the outer most home signal and the one in the rear of that could be a distant signal?

[LMS2968]

That's right! And the one after that is the Starter from the box in rear (or IBS signal), and so it goes on.

[ElectroSoldier]

And if its not a distant signal it would be an Intermediate Block Home Signal?

[LMS2968]

No, there would still be a distant; there would also be a distant for the IBS in the normal way..

[LMS2968]

This might help.

[big jim]

the other thing about that signal is it doesnt have TPWS fitted which i thought was pretty standard for a signal protecting the junction nowdays, especially that close to the junction

 

if i remember right the signal before it on the st helens line is a semaphore stop signal, as you can see the rear of it when you pass by on the chat moss line

 

beast66606 and flyingsignalman are your men for signalling on this line!

[ElectroSoldier]

This might help.

 

I see how it works now thank you.

 

So "A" would also have a distant signal, and might also have and outer and inner home signal depending how long the the section is between the absolute block section and station limits?

And station limits is the section between the inner most of the home signals and the starter signal?

[LMS2968]

Nearly there! The section would be between A's Advanced Starter and B's Outer Home (assuming no IBS). Between the Outer Home and Advanced Starter was called Station Limits, and shunting could take place between the Inner Home and Starter and trains be in section either side of these, provided the quarter mile clearance was available from the stop signals outside of them.

[ElectroSoldier]

So station limits always started in advance of your first stop signal after the distant (Outer home?), and it ended in rear of the outer most stop signal? and that outer most stop signal was usually an advance starter but on a route that is quite long it would be an Intermediate block home signal?

Would the Intermediate block home signal always have a distant signal?

How long would the line have been in order to have an Intermediate block home?

[corneliuslundie]

I think you are misunderstanding the purpose of Intermediate Block Signals. They effectively form an unmanned "automatic signalbox" between two boxes to break up a long section and give greater line capacity (someone please jump on me if I am wrong). They are not actually that common so probably best to forget the idea when trying to work out block signalling. And I am not sure how they link in communication and interlocking terms with the adjacent boxes.

Your maximum sequence of signals when going passing a signalbox will normally be distant; outer home; inner home; starter; advanced starter. The minimum will be distant; home; starter (and on a single line the distant may be fixed at caution). The others are to give more flexibility of operation within station limits. There may also be repeaters if there are visibility issues, but as the name suggests they simply show the same as the signal to which they are linked.

The information above about clearance distances and station limits is very clear so I won't comment on that.

Jonathan

[The Stationmaster]

So station limits always started in advance of your first stop signal after the distant (Outer home?), and it ended in rear of the outer most stop signal? and that outer most stop signal was usually an advance starter but on a route that is quite long it would be an Intermediate block home signal?

Would the Intermediate block home signal always have a distant signal?

How long would the line have been in order to have an Intermediate block home?

Station Limits runs from the rearmost (outermost) stop signal (i.e. the first one a reached by a train travelling in the right direction) to the Section Signal, which is the most advanced stop signal and the one controlling entrance to the block section in advance.

 

In the normal arrangement of such sections the Intermediate Block Section commences at the Section Signal and ends at the Intermediate Block Home Signal - what then follows (unless there is a second intermediate section) is the Block Section between the signal box in rear and the signalbox next in advance.

 

 

Let's start at the beginning in the hope we can clarify things?  

 

A Block Section runs from the most advanced stop signal (known as the Section Signal) at the signalbox in rear to the outermost Home Signal of the signalbox in advance - i.e. at the advance end of the section.  There will be no intermediate signals of any sort apart from the Distant Signal for the 'box in advance.   But as already explained a block section can be split by inserting an Intermediate Block Section.

 

Station Limits runs from the outermost Home Signal of a signalbox to the Section Signal.  The use of names for signals can be a little confusing so in thinking of both Station Limits and the Block Section just think of the terms I have used - the reason for this is that on the LMR the outermost Home Signal was called 'Home 1' while on the GWR and WR it was called the 'Home Signal' while some other Companies/Regions might use the term 'Outer Home Signal' - none of that matters, the critical thing is that it is the outermost Home Signal and marks the end of the Block Section and the start of Station Limits.

 

Similarly with the Section Signal as it too can have numerous names all of which derive from past Company/Regional practice and depend entirely on the number of stop signals there are on that line at that signalbox and, usually, their position in relation to the signalbox.  That is one reason why I prefer to always use the relatively modern term 'Section Signal as it is completely unambiguous and it marks the end of Station Limits and the start of the next Block Section.

 

The matter of naming, as already indicated, could vary quite considerably especially on Companies like the GWR which tended to be fairly liberal in the provision of stop signals on running lines - for example 'Outer Advanced Starting Signal' is quite a mouthful, but it was still - at one 'box I knew well - the Section Signal.

 

To answer your final question Intermediate Block Sections were normally used to fairly evenly split the length of a section between two signalboxes although the tendency was to site them nearer to the signalbox in rear (i.e the one which worked them) in order to reduce the length, and cost, of providing a track circuit.  On the GW/WR mainline from Paddington to Bristol the various IB sections between Reading and Swindon mostly split section which were around 3 miles long.  This meant that by dividing them the longer block sections became not much different in length from the shorter ones where signalboxes were closer together and this improved and increased line capacity without the expense of providing what were known as 'break section' signalboxes.

[LMS2968]

Corneliuslundie and Mike the Stationmaster have given you the answers here, but I'd like to add a bit. I think I should point out that my time on BR was spent in brake vans at the rear of goods trains, so while I have a fair knowledge of Block working, it doesn't compare with that of Mike and others on this board.

 

Don't get too hung up on IBS. Often they were established when a simple block post box was eliminated for economy reasons, but the resultant length of the combined blocks would be excessive. IBS became a cheaper alternative to a signal box and - even more so - a signalman. Adrian Vaughan gives a good run down of their working in his book 'Obstruction Danger' (1989, Patrick Stephens Ltd, ISBN 1-85269-055-1) in the chapter on Hellifield in 1955. This was a rear end collision, caused in part by misuse of the IBS. Strangely, in this case the IBS was controlled by the box in advance, something I though rather odd. Certainly, the collision would not have occurred had the box in rear had control. I've attached the report, but this has less explanation of how things worked.

 

Most boxes would have Distant, Home and Starter signals only; Outer Homes and Advanced Starters would be supplied only against a specific need. This would usually involve a junction, but also if shunting across the main lines would be fairly common. Extra signals involved extra expense, and an outer home would involve the Distant's being moved back the appropriate distance to give adequate braking. This distance involved a longer signal wire, more maintenance, greater need to use the slack adjuster and a harder pull for the bobby.

MoT_Hellifield1955.pdf

[phil-b259]

This might help.

 

I hope MLS29868 doesn't mind but I thought that his diagram could be improved to visually illustrate of a couple of terms which some find confusing

[beast66606]

The controlling signal box was Huyton - this was previously Station but was renamed Junction when the Junction box was abolished in the 1950s (iirc) and control of the junction was put onto the station box. All gone now of course with the electrification sweeping it all away.

 

The arm was removed from the gantry when the Huyton - Edge Hill main line was resignalled to increase capacity in the 1990s. The disused dolls which used to control the two double junctions allowing trains to run to/from St Helens and to/from Earlestown are also visible in the photo - it was four tracks from Edge Hill to here and then two to St Helens and two to Earlestown until rationalisation arrived in the 1970s.

 

Correcting a couple of points.

 

The minimum typical signalling is a distant and a home but as has been mentioned distant / home / starting was the most common. 

 

IBS were quite common on the LMR but not so on the L&M - Edge Hill No.1/Lime Street had some at Brownlow Hill.

On the WCML some of the small boxes controlled their own signals and two IBS in each direction which must have been interesting when things were busy and the trains were getting checked, remembering which train you were actually belling to the next box, as you shuffled them along the sections - of course good booking in the book would help the bobby keep on top of things. IBS were normally in advance of the signal box - i.e. you pass the box before the IBS but on occasion they were in the rear, you got to the IBS before the signal box. 

 

As LMS says, don't get hung up on IBS, they weren't used on the L&M.

 

Huyton Junction was one of the boxes I visited - and even had a go at - in my days of being a free signalmans assistant. One day I'll get around to scanning the photos I took.

[The Stationmaster]

I hope MLS29868 doesn't mind but I thought that his diagram could be improved to visually illustrate of a couple of terms which some find confusing

Perhaps it would be better to  re-do it more accurately please Phil - thus show the whole of Station Limits in the same colour (red) and then overlay the Clearing Point (there is no such thing as an 'overlap' in any of the traditional block systems) ina  contrasting colour if you wish.

 

The Clearing Point lies within Station Limits (there wouldn't be much sense to it if that wasn't the case) and is not and never has been part of the block section so it would be much less confusing if you could correct your little diagram.  Incidentally your comment about more than one train at a time in Station Limits is a little ambiguous - while you can have more than one train in Station Limits you are still only permitted to have one train at a time in a Signal Section unless some form of Permissive working is authorised.

[beast66606]

Further to my comments regarding IBS being uncommon on the L&M, my brain has just awoken and reminded me that when Huyton Quarry was abolished in the 1970s, an IBS was provided, controlled by Huyton Junction  - doh ! - a colour light home with a motor worked semaphore distant.

[phil-b259]

Perhaps it would be better to  re-do it more accurately please Phil - thus show the whole of Station Limits in the same colour (red) and then overlay the Clearing Point (there is no such thing as an 'overlap' in any of the traditional block systems) ina  contrasting colour if you wish.

 

The Clearing Point lies within Station Limits (there wouldn't be much sense to it if that wasn't the case) and is not and never has been part of the block section so it would be much less confusing if you could correct your little diagram.  Incidentally your comment about more than one train at a time in Station Limits is a little ambiguous - while you can have more than one train in Station Limits you are still only permitted to have one train at a time in a Signal Section unless some form of Permissive working is authorised.

 

Doh!

 

My lack of mechanical signalling knowledge (versus MAS) showing through again.

 

As for station limits, yes I did not make it clear that one train per each signal section within the station limit section still applies unless, as you say some sort of permissive working has been specifically installed. It was also intended to show that within station limits you can have many signal sections while each block section cannot have any intermediate signals (apart from possibly those protecting level crossings?) because to do so would allow the one train rule to be broken. Intermediate block signals, by breaking the block section into two discrete sections get round this issue of course.

 

Also I believe that the whole basis behind the clearing point in mechanical signalling is to provide a safety margin beyond the Home signal governing the exit from a block section and it was thus similar in principle to the 200yard overlap beyond a colour light signal. Thus it is a signalling principle that the signal section must have the section of line between the home signal and the clearing point (440 / 200 yards) free of trains* if a train is permitted to enter the block or signal section the overlap / clearing point is associated with.

 

*I know there are various provisions to allow this to happen in mechanical signalling principles - and under MAS you have 'Warner' routes / approach control / restricted overlap exit buttons to do the same.