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> A question on signal placement (bridges)
Ryan Allington
post 11 Oct 2018, 23:09
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Hi All,

I'm currently working on a track plan to get started on early next year (read as: when I have time and funds, and I'm happy with my current project). It's a single-track branchline terminus set in East Anglia late-50s. The issue is the plan at present places a road bridge immediately before the station to serve as a scenic break. Since the bridge would block sighting of the signal from the driver's perspective, I gather it would be placed in front. Here's the problem: the starting signal has to be behind the bridge for the same reason or the train can't see it from the platform - where do I put the signal box? My understanding is that the signals also had to be visible to the signalman so he could confirm the signal was set? Or is this a simple case of using a co-acting signal so the loco crew/signalman can see the aspect over the bridge?

For clarity, the station has one platform, with a run-around loop and a turnout to an engine/goods shed (I haven't decided yet).

Thanks.
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jim s-w
post 11 Oct 2018, 23:26
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If it’s a single line terminus then it might not have any signals or a signal box at all. The nearest signal box could be at the junction at the other end of the branch.


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Please feel free to visit my workbench http://www.p4newstreet.com/category/workbench all comments welcome.
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John Webb
post 12 Oct 2018, 08:33
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It would depend on how the rest of the branch was signalled - if by "One engine in steam", then once given the train staff at the junction station, the sole locomotive on the branch would not strictly need any signals at all, so the terminus would have no signals and all points would be worked by the train crew. From the description of the limited facilities on your proposed model, I think this is the most likely scenario.

Had you had a siding or two for freight purposes (not all goods could be dealt with in a shed - particularly coal, for example) then it might be possible for the passenger or the freight train to be 'locked in' to the platform or goods yard to allow a second train to run using some form of 'Token' system. In which case there would be a signal box and a few signals. But the box could be a modest platform-mounted one or even adjacent to or part of the station building. In which case the starter signal would be at the end of the platform.

It wasn't completely necessary for the signalman to see the signals - there are ways in which the position of the signal can be repeated back to the signalman by fitting an electrical switch to the signal arm and having a repeater in the signal box, as seen here:

in the preserved St Albans South box. The round dials along the face of the block shelf above the levers are signal repeaters; the two nearest the camera are showing signals at 'Clear', the next two are showing signals at 'Danger'.

Regards,
John Webb
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Ryan Allington
post 12 Oct 2018, 22:14
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Thanks for the advice, Jim and John. The intention is the line itself would have a passing place at one of the intermediate stations (to facilitate increased traffic on market days, etc. which I recall being a consideration on some Suffolk Branches in 'Suffolk's Lost Railways'), so I imagine a signalled token system might be the most accurate approach. It has also occurred to me that I'll have to take into account with the Home Signal that there needs to be sufficient space between it and the run-around to allow for shunt-limits? Although given token working only allows one train along the section at a time, something pretty bad would have to go wrong for two trains to end up at the station in the first place.

Unless I'm missing something glaringly obvious, which is entirely possible (nee, probable). wink.gif
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John Webb
post 13 Oct 2018, 09:37
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If there is a passing place elsewhere along the branch, then it is possible that the Main Line Junction > Passing point would be worked by a token system and the Passing point > Terminus would be "One engine in steam" to save on the expense of a token system and signals at the terminus.

If you decide to have signals at the terminus, then you would probably need two - a starter at the end of the platform and a ground disc signal at the loop exit onto the running line (don't forget the trap point on the loop, although the siding into the shed could be used as that!). The opposite end of the loop by the buffer stop would probably be worked by the train crew. The home signal would be a little way down the line on the approach to the station, so out of sight beyond your scenic break and therefore need not be modelled - likewise a 'Limit of Shunt' sign would be near the home signal, so again need not be modelled. With a signal box on the platform or at the station throat in sight of all shunt moves, it is unlikely that there would be any other ground signals.

John
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Ryan Allington
post 14 Oct 2018, 22:51
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QUOTE (John Webb @ 13 Oct 2018, 09:37) *
If there is a passing place elsewhere along the branch, then it is possible that the Main Line Junction > Passing point would be worked by a token system and the Passing point > Terminus would be "One engine in steam" to save on the expense of a token system and signals at the terminus.

If you decide to have signals at the terminus, then you would probably need two - a starter at the end of the platform and a ground disc signal at the loop exit onto the running line (don't forget the trap point on the loop, although the siding into the shed could be used as that!). The opposite end of the loop by the buffer stop would probably be worked by the train crew. The home signal would be a little way down the line on the approach to the station, so out of sight beyond your scenic break and therefore need not be modelled - likewise a 'Limit of Shunt' sign would be near the home signal, so again need not be modelled. With a signal box on the platform or at the station throat in sight of all shunt moves, it is unlikely that there would be any other ground signals.

John


Okay, thanks. That makes things nice and clear.
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Bear 1923
post 15 Oct 2018, 09:13
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cool.gif I've been away...

Several issues arising...

1. Operating system.
One Engine in Steam is possible. I'm not sure that it would occur in the dead end beyond a passing loop after any other line - such as from a junction (as John has suggested).
Given a passing place I suspect that the whole line would be worked using a form of staff or non ETB token. Each Block Section's staff would be labelled and distinctive to show clearly to which Section it belonged. It is possible that the Section from Junction to Passing Place would be either a divisible staff (i.e. one or two parts could be unplugged from the main body to send one or two trains ahead - always followed by the main body before anything could work in the opposite direction). The other possibility for this Section would be Staff and Ticket working (much the same as a Divisible Staff - but paper tickets are issued instead of parts of the Staff).
Within this arrangement using staffs the terminus Section is unlikely to need more than a plain staff. It seems very unlikely that there would be room for more than one movement at a time at such a small terminus.
Okay - so - only one staff does sound very like John's One Engine in Steam... but One Engine in Steam is a very specific working arrangement (which doesn't necessarily have to have a staff - if the loco is "locked in". Locking in would be more of a kerfuffle than giving the train crew a staff.

2. Signals.
Hmmmm...
Running Signals
I think that the absolute minimum would be a Fixed Distant on the approach to the terminus. Basically this would provide train crews with a marker point at which to start braking - ready to stop. So - a Distant Signal would be placed at the Service Braking Distance from at least the toe of the first points - OR - a Home Signal if one were provided.
IF there were any other signals the two Running Signals that would be required would be a Home Signal - 440 yards out from the toe of the first points - possibly a bit more. (440 yards is always the magic distance when dealing with Block working - until recent times and when a Colour Light Distant is provided). The other signal would be - as John suggests - a Starter form the platform end. Basically these two signals would allow into and out of the station. By the 1950s they may have been done away with as an economy measure. Stumps of the signal posts might remain - varying between cut off at ground level and about 12-18 inches - unless cut at about 6 feet to provide a notice post.

IF there are Home and Starter there would possibly also be an Advanced Starter - when leaving the terminus this would be found before reaching the Home or across the line from it... This sets up a whole load of questions though - which I have not seen resolved. The issue is whether and if so when any shunting is "In Section" and should therefore hold the Staff - or - at least be "Blocked Back" to the next Box.
Those are the Running Signals.

Non-Running Signals.
Shunts/Ground Signals in this case.
IF there were any Running Signals I suspect that a shunt might be provided out of the loop as John has suggested.
IF there were an Advanced Starter we might get a shunt signal into the loop - this is more likely if a siding were accessed in the same direction (from the Running Line).
The question would be where to locate an "inbound" shunt signal. In standard practice I think that we would need to end up with both Inner and Outer Home signals. The Inner being just before the points and the Outer 440 yards In Rear of that. The Inner Home would then signal into the platform and have a shunt signal with it into the loop/siding. This is getting expensive for a very small station... Which raises the question - what traffic is paying for all these signals, their connections, operation and maintenance?

So - I suspect that the most likely thing would be only a Fixed Distant.

3. Traffic and Working.
What traffic is paying for this station???
Why (on earth) would a loco be stabled at the end of the branch at such a small station? Crewing, water and coal supply - and some level of maintenance would have to be provided. (As well as maintaining a shed - IF one were provided.
First train out in the morning??? So? What stock and where are you going to stable it?
So - I would go for some level of goods facility.

Passenger service (IF ANY) in the 50s? Auto-trailer or single car diesel. This would make the loop redundant except for goods - but could mean that traffic could be loaded on the loop.

4. Sighting (or not) Signals.e
As John has illustrated signals out of sight of the signalman would be provided with electrical repeaters. These were in use right back before 1900 - and Required by the Board of Trade.
From the train crew perspective signals MUST be in clear view from a suitable distance - according to line speed, weight of trains, gradients, curvature, etc. This can be achieved by placement - bearing in mind that an Inner Home would usually be located up close to the toe of the points that it protected.
Where any structure tended to obscure the sighting a tall signal with a co-acting repeater could be used as the OP suggests. One alternative would be a gallows signal to place the arm where it could be best seen under a bridge or platform canopy. (Sometimes a co-acting arm would be on a gallows arrangement). Another solution would be to place the signal "Wrong Side" - i.e. across the track - on the right as seen by the approaching train crew - this might still be a tall signal and repeater. Last but not least - a Banner Repeater could be provided on the approach to the signal itself. A Banner Repeater co-acts with the signal itself.

5. Signalbox.
I thin that the question is not so much where but "if?"
With passenger traffic points and signals MUST be interlocked. With no signals there would still have to be means of locking the loop points - probably with a Facing Point Lock (FPL) locking the points in the 4 foot way. Either scenario would more likely be achieved by using a Groundframe. This is unlikely to have been raised and not very likely to have any weather protection - it might live in a tiny shed. The location would be either mid way between the points into the loop and the trap points or beside the points into the loop.
It seems to me most likely that the groundframe would normally be locked out of use (to prevent tampering) - and that this would be achieved with an Annette's Key (or equivalent) on the staff. (An Annette's Key locks/releases a controlling lever that release/locks all the other levers.
The other levers would be for the access to loop points and their FPL - and any Stop or Shunt signals - if there are any.
The dead end of the platform/loop points would probably be on a local ground lever - which would be "trailable" - i.e when the blades weren't set for the movement required they could be pushed through - "re-setting" them for the movement by the movement itself.

I think that I have covered most items cool.gif
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