Drummle

On 26/10/2021 at 12:18, The Stationmaster said:

Don't forget that it was quite common to have a signal box at each end of stations if the track layout so required and teh distance between signal box and the points it was permitted to operate left no alternative.  At many smaller locations gradual relaxation of the distance allowed between signal boxes and the points they worked allowed the location to be reduced to a single 'box and much of this went on in the 1930s in order to reduce the wages bill.   But even at some relatively straightforward double line stations two signal, around a quarter of a mile or so (or less) apart survived into the 1960s.  And of course numerous parts of the Signalling regulations made provision for closely spaced 'boxes and the signals they worked.

This is exactly the scenario I'm considering and given how common it was it's surprising how little there discussion there is in the various online sources of the situation! If I ever come to feel authoritative enough maybe I'll put a page up myself, but that's clearly not yet...

I believe that the other reason for this arrangement would be (on busy lines) to allow the signaller at the relevant end of the station to give "train out of section" at the start of the station stop on sight of the tail lamp — if there were only one box then a train approaching from the opposite end of the station could not be given "out of section" until it had completed its stop and the tail lamp had passed the box.

On 26/10/2021 at 12:18, The Stationmaster said:

First there is/was no problem at all in having  a station platform in a block section that was bi-directional because it is simply signalled as a single line section using whatever method would be suitable for such a line.  Not particularly common but not impossible.  Shunting in either direction was very common but was covered by other procedures so the line would not be signalled as a single line for that purpose.

Would you mind elaborating on "whatever method"? Was/is there an alternative to the use of train staff or token operation that would be more suitable for this situation? I have seen diagrams featuring "acceptance levers" which I guess have something to do with it?

On 26/10/2021 at 12:18, The Stationmaster said:

Secondly running an engine round a train which s. is standing in a block section is a very straightforward procedure which could be done in any double line Absolute Block section provided that it was not specifically prohibited (usually because of gradients although sometimes various other reasons might apply).  On a single line there is/was no similar Regulation for the simple reason that you cannot run round a train which is in a single line section as there is no other line for the engine to use (although a through siding might exist).  Thus if there was a need for such a procedure it would normally be covered in the signal Box Special Instructions although I can't immediately think of anywhere that it would have happened.

Would you mind explaining how this would be done or referring me to the relevant regulation if it's available online?— I am stumped at step 5 in the below.

1 Train comes to a stand in the block between [A] and : block instrument shows "train on line"

2 Loco pulls forward to 's station limits; gives "engine arrived" and instrument remains at "train on line"

3 Loco uses pointwork at to change lines and returns to [A] in the usual way

4 Loco uses pointwork at [A] to return to the original line

5 ??? Loco now needs to enter the block between [A] and which already has a "train on line"!

6 Train exits the section in the opposite direction at [A]

7 [A] signals "train withdrawn" and returns block to normal ("line blocked")

Many thanks again

Sam

19 minutes ago, RailWest said:

In all the above new examples, the 'Up Starter' at the START of the platform IMHO is superfluous, as all moves into the platform could be controlled by the stop signal in rear or a shunt signal at the Down line end of the crossover.

 

Likewise in C1 and C2, as there appears to be no pointwork or other potential obstructions between the Down Home and Down Starter, then one of those is superfluous also.

Thanks, so helpful.

On the up side, makes sense to remove the West starter. Still not sure how the shunt into the occupied platform block could be authorised though!

On the down side of C, the East down home positioned where it is means a wrong line move to run around would be blocking back inside rather than outside the home. Naïvely I'd expect that to be preferred but maybe not? Perhaps depends only on whether traffic is dense enough to make the option for East to accept traffic from further up-line under the Warning Arrangement?

Thanks for the diagrams Mick. I still can't make head nor tail of when to use which of the following!

But at least I've learned something...

On 22/10/2021 at 22:45, Wheatley said:

Railwest has it. The block section is the bit from the last controlled stop signal of one box to the first controlled stop signal of the next box. Station limits is the first to the last of the same box.

 

In your first diagram West has no station limits and the block section is the green bit. 

 

Stations do not have to be within Station Limits, and Station Limits do not have to have to have a station in them. To assume otherwise is a modellerism.

Thanks for this (also to Chris). (I’m afraid I’m not sufficiently au fait with the railway geography of Barnsley to understand the other use of slotting you outline, but I think that is quite a different purpose so will leave that be!) Here’s an amended diagram as per your explanation and without modellerisms (I hope).

I do understand that there's the alternative of having the platforms in the block section rather than within station limits, but didn't think this would be applicable when the platform is operated bi-directionally as in my second two examples? Having thought some more, though, this is how I think “B” would now look:

In the specific case of an “up” train being run-around in the station, I assume that it would be accepted into the block by East as normal; the engine would detach and East would advise West “Engine Arrived” before sending the loco back down the loop, which is now a second block operating in the opposite direction. But how would the loco then be signalled back into the platform (which is now a block occupied by the carriages of the train), though? This is why I’d assumed the platform had to be within somebody’s station limits in this case.

The same question applies in my example C (below), with the addition that the platform road itself is reversible; and thus I guess would have to be fully protected by tokens etc.? (The complete layout would have a trailing connection into the up main from a branch, so the reversibility is necessary.)

Thanks again for the thoughts so far, every day really is a school day!

Sam

I’ve been trying to get my head around the signalling arrangements at stations governed by more than one signal-box. I think (famous last words) that I understand the principles, but I’d be grateful for any help putting them into practice!

The first two diagrams below show what I think would be a fairly normal set-up in which the box in rear (“West”) has its starter signal slotted with the home signal of the box in advance (“East”). Black sections show the block controlled by each box, and green sections are station limits.

Is it correct that the East box (in advance) has no actual block under control, and thus that “Is Line Clear?” posed from West to East relates only to the ¼-mile overlap in advance of the East home signal? Or to put it another way, that West could run a train up to the East home without consulting East at all?

In my mind the West starter / East home signal is slotted at the post just like a home/distant signal, thus the starter lever at West could be pulled but the arm would remain “on”. In that scenario would the West signaller be required to observe rule 39(a) and caution a train at their own home signal, and would this rely on their attentiveness to the actual position of the starter/home arm or maybe a reminder device? Or am I completely wrong and there would actually be some kind of mechanical interlock between the boxes themselves so that the starter lever couldn't be pulled until East had pulled their home lever? Maybe this is situation specific, thinking about it.

(In the diagrams I’ve showed slotted signals with the arm showing the most “urgent” restriction in the horizontal position but I’m not sure if that's correct. The distinction in the RSSB guidance previously shared on this forum seems to be between “slotted by” another box and “slotted at” another box which is clear as mud to me!)

If I’ve got things right so far, then I guess that in the above example (considering only the West box now) that a loco headed “up” from West to East could run around its train under the control of the ground signals A and B and head off back down-line without troubling the signaller at East.

On the other hand it wouldn’t be permitted for the loco to pass the West starter (aka East home) before reversing unless there was a special instruction to allow working in the wrong direction back into East’s (zero-length!) block, and presumably special interlocking / acceptance levers? (I guess this is what acceptance levers are for, I’ve seen them on SB diagrams but never understood their purpose without being able to cross-reference the local rules of course.)

Finally before my head explodes, would a scenario like this be practical? Again the signals shown as “active” are controlled from the West box, and although it looks contrived in isolation(!), in effect the platform road here is just like a bidirectional platform in a larger station (or the “back road” at e.g. Ely).

As I see it the East signaller can safely pull off his starter (which is actually a slot on both arms of West’s down home as shown – I guess one lever would suffice for this) and thus give a train the right away into the reversible platform! Part of me feels like this must be wrong as there “ought” to be a token or suchlike before a train can be released into a bidirectional track, but is it actually all ok because that track is entirely within West’s station limits and the signal doesn’t actually clear until West is good and ready and has also pulled a lever?

Hopefully some more knowledgeable than me can help here, and if so many thanks in anticipation! I’ve been a longtime lurker on here and am always in awe of the expertise on offer…

Sam