Signalling - two trains in one platform

[tender]

I've been asked to look at the signalling for our local 5" gauge track. I know its more model engineering than railway modelling but the operation will be akin to a single track roundy roundy with block signalling to keep the trains apart using 2 or 3 aspect signals.

 

The problem arises at the Station where the Platform is split in two halves one behind the other, similar to having a platform 1A and 1B in the prototypical world.

 

A Train arriving at platform 1B would unload its passengers before moving forward to 1A to load new passengers. While this is happening a following train would then be allowed to move into platform 1B to unload. When the first train leaves platform 1A the second train moves forward to 1A etc. etc.

 

This is where my signalling knowledge leaves me a bit blank and i wonder if there is something of a prototypical way of signalling this. 

I have seen on several occasions two trains in one platform (at Chester for instance) but never really looked at signalling.

 

Any help appreciated.

 

 

[andyman7]

I'm a bit rusty on my signalling knowledge but hopefully others will contribute more, however what you are describing is a form of permissive block working which essentially in specific conditions allows a second train into an already occupied section. Permissive working is more common on non-passenger lines but it is (as you note) also used with passenger trains in station working where more than one train can occupy a platform.

 

In each case the local signalling regulations will denote the particulars of the permitted working (approach speed that must be observed, stopping points and any other details); the signal that permits working into the occupied section will be equipped with a suitable indication (for example a theatre type box or a calling on indicator) that will denote that the train is being permitted into an occupied section subject to the aforementioned rules.

[Suzie]

You will realistically need to put a signal half way down the platform and think about using a signal that can indicate restricting.This signal has no overrun after it if a train is parked in the platform so you will need to mitigate that when signalling a train into the set down platform when the pick up platform is occupied.

 

From a model engineering aspect I would have a call-on signal half way along the platform so that a train (without passengers) can be moved in to the pick up platform before the previous departing train has departed the block. As to approaching the set down platform that gets a bit tricky, but I guess that the same can be done on the signal approaching the platform so that the driver knows he has to stop short of any obstruction (because you know there is something there within the area that would normally be clear).

 

There are a few ways of indicating a restricting aspect, the two white light at 45 degrees is probably the best way of doing it.

 

Historically there have been other ways of doing this, and LMS 'New Lines' signalling might be worth a look but it is a long way from 'Simple 3-aspect'.

[Phil Bullock]

GW did it with this...

 

http://www.bing.com/images/search?q=worcester+shrub+hill+signals&view=detailv2&&id=F1C1C9B23884E13986EDA4EE646C05FCC3E474F0&selectedIndex=16&ccid=R35RyjlM&simid=608031249567647323&thid=OIP.M477e51ca394c8f039c8f5a63fe2b9896o0&ajaxhist=0

 

Kind regards

 

Phil

[Grovenor]

You don't "Need" a mid platform signal, they were more common if there was a mid platform crossover (as at Cambridge). The simplest solution is just to have a "call on" aspect on the signal leading into the platform. If you are using track circuit control divide the platform into two track circuits. Allow a yellow for entry when both track circuits are clear, allow the "call on" when only the rear track circuit is clear and the forward one occupied.

Regards

[Mike Storey]

I agree with the principles of signalling above, but I would strongly suggest, if not already done, that a trap point is laid between the two halves of the platform (or a point diverting to a loop, to safely by-pass the stationary train). The greatest risk, once some form of warning by signal that the platform is partly occupied, is of brake failure (or mis-judgement by the driver), and a resulting collision.

 

If this is not practical, then you should adopt a strict practice of halting all arriving trains outside the platform, before allowing it to draw forward under a calling-on signal or similar (which used to be standard prototype practice, at least on the SR, until approach controlled signalling became common). This allows a length of overrun if the brakes have degraded or failed (or the driver has mis-judged the braking), and would, in the worst situation of complete failure, reduce the collision speed.

[Coryton]

You don't "Need" a mid platform signal, they were more common if there was a mid platform crossover (as at Cambridge). The simplest solution is just to have a "call on" aspect on the signal leading into the platform. If you are using track circuit control divide the platform into two track circuits. Allow a yellow for entry when both track circuits are clear, allow the "call on" when only the rear track circuit is clear and the forward one occupied.

Regards

 

Having two (or more) trains in a platform without intermediate signals is certainly not unusual on National Rail. I think the driver of the rear train has to be hand-signalled to give permission to draw forwards once the train in front has departed.

[Phil Bullock]

I agree with the principles of signalling above, but I would strongly suggest, if not already done, that a trap point is laid between the two halves of the platform (or a point diverting to a loop, to safely by-pass the stationary train). The greatest risk, once some form of warning by signal that the platform is partly occupied, is of brake failure (or mis-judgement by the driver), and a resulting collision.

 

If this is not practical, then you should adopt a strict practice of halting all arriving trains outside the platform, before allowing it to draw forward under a calling-on signal or similar (which used to be standard prototype practice, at least on the SR, until approach controlled signalling became common). This allows a length of overrun if the brakes have degraded or failed (or the driver has mis-judged the braking), and would, in the worst situation of complete failure, reduce the collision speed.

Having visited our local model engineers I suspect we are talking of an oval of plain track here ... they usually run on an elevated pier system about 2 - 3ft off the ground which probably dictates against any arrangement with trap points or loops. IIRC our local club runs under the arrangements suggested in Mike's second paragraph above - they have semaphores but with Colour lights if there is a train in the platform could approach signals read amber two blocks out then red at platform approach block and half way down platform - signal at platform approach then has a shunt aspect to proceed in to the platform but stop at the next red half way along.

 

Would that work?

 

Phil

[melmerby]

London Midland trains regularly join and divide at Northampton but I haven't noticed halfway signals.

Maybe somebody in the know could enlighten me?

 

It also happens in B'ham New St but there are midway signals

 

Cheers

 

Keith

[Coryton]

London Midland trains regularly join and divide at Northampton but I haven't noticed halfway signals.

Maybe somebody in the know could enlighten me?

 

It also happens in B'ham New St but there are midway signals

 

 

It's common for two or more trains to be in platform 2 at Cardiff Central without intermediate signals. It's not even for trains to join - it just allows a train to pull in and have the water tanks filled and reservation tickets put on before the preceding train has left.

 

If there are intermediate signals, then the need to provide an overlap (and - these days - to stop well before the signal is reached) means quite a lot of space is needed.

 

Bristol Temple Meads is a special case - there are midway signals but they are fixed illuminated boards. So far as I know, permission to pass the board is given by a theatre indicator giving the number of the platform which is beyond the board (the two parts of the platform have different numbers).

[tender]

Many thank for the quick responses. A lot to take in and some names I'm not familiar with. Will spend a few hours taking all this in and post a proposed plan for comments.

 

Edit.

Forgot to add - the track is a raised level 5" gauge so no turnouts/traps etc.

[Grovenor]

then has a shunt aspect to proceed in to the platform but stop at the next red half way along

The stop signal halfway along the platform has no benefit, if the loading train is still there the rear end of the train is at least as obvious as the signal would be.

If the loading train has already gone the driver knows the procedure of stopping, unloading and drawing forward to load, and with nothing in front a small overun would not hurt. It would make sense to have a stopping marker for this situation however.

Regards

 

Nb. A 5" gauge railway does not have to follow Network Rail rules, but for carrying passengers need to have their own rules and do a risk assessment to show they have considered the likely issues, such as brake failure. I would expect their insurer to be insisting on something on these lines.

[tender]

So, no signal half way along, but something like this

 

 

just before the platform entry.

[Suzie]

Make it approach controlled, and perhaps you can have a pop-up hydraulic bufferstop half way along the platform in lieu of a catch point - much easier in 5" than 4'8"..

[leopardml2341]

TPWS?

 

Hat, coat and wild blue yonder......

 

Sorry couldn't resist.

[Boco_D1]

On the network permissive working of trains into platforms is permitted by the signal box special instructions, which describe what type of train and under what circumstances it is allowed. Trains tend to be signalled by the use of calling on signals that inform the driver that the platform is already occupied. The driver under his training should know at what speed to proceed into the platform.

[Pandora]

This is easy, when track circuits in the platform, show "not occupied" ie no trains berthed, the signal interlocking allows a non-danger proceed aspect, single yellow or less restrictive.

 

If the platform is occupied and the track circuits allow,  the signal will be a call on, two white lights and a danger  main aspect, the driver can proceed on the authority of the two whites and pass the main aspect at danger, driver must proceed with caution, prepared to stop at least 6 feet from the train berthed ahead.  This is PP permissive passenger working. There is also PG, permissive goods, same thing allowing freight trains into sidings.  Additionally when PP is allowed, (it is shown in the Sectional Appendix track diagrams)  normally, goods trains cannot enter a platform occupied by passenger stock,  the Driver of the goods train will contact the Signaller for verbal authority for the movement

[Grovenor]

So, no signal half way along, but something like this

 

3cl_calling.jpg

 

just before the platform entry.

That will do just fine so long as your rules define the meaning of the small yellow as something on the lines of, "Platform partly occupied proced with caution and stop in discharge position".

Regards

[the penguin of doom]

On the network permissive working of trains into platforms is permitted by the signal box special instructions, which describe what type of train and under what circumstances it is allowed. Trains tend to be signalled by the use of calling on signals that inform the driver that the platform is already occupied. The driver under his training should know at what speed to proceed into the platform.

We had this special instruction when I worked at Bridlington where the block section included a through platform. If the up platform was occupied, special bell code was sent before allowing a second train to proceed into the section under the authority of a colour light calling on signal, (main aspect remained Red and the calling on signal showed 2 x diagonal white lights).

 

In another box, we signalled trains into an occupied bay platform using a semaphore calling on arm below the main signal. The calling on arm was about 2/3 the size of the main arm and had a horizontal white stripe on a Red background if that makes sense? I will try and find a picture of the arm concerned to explain it better.

 

In both cases, the occupation of a track circuit prevented the main signal being cleared.

 

Cheers.

 

Sean.

[The Stationmaster]

So, no signal half way along, but something like this

 

3cl_calling.jpg

 

just before the platform entry.

Now you're getting there.  The simple way to do it is as follows -

 

1. Signal your line with 3 aspect or 2 aspect colour light signals auotmatically operated by passing trains except where you need to control them to red for some reason.

 

2. The signal protecting the platform should be a controlled signal in any case - all trains must be brought to a stand at it before either

a. operating it to as proceed aspect if the platform is empty, or

b. operating the 'calling on' aspect (a white light would be suitable) to signal a train to the rear half of the platform while the advanced end is occupied.  The train may only work forward to the advanced end of the platform when the line is clear to the next signal in advance and the Driver receives authority to move from the person in charge of the platform.  The next signal in advance must be in clear sight of the platform.

 

Essentially you only need 2 aspect signals because speeds are low and (hopefully) signal sighting will not prevent a problem.  But 3 aspect would be quite ok if you're prepared to pay the extra for them.

 

I have no doubt at all that the above would be acceptable to your insurers but you - as a society - must ensure that persons who will take charge of the platform are properly trained and that training records are maintained (and for Drivers).  As an additional safeguard the signal protecting the platform could be arranged to normally stand at red and a treadle or track circuit be operated (with timer if necessary) to allow it to be cleared to either of the proceed aspects in order to ensure that an approaching train is stopped before getting a proceed signal.

 

(n.b. no charge for the above proposal)

[Coryton]

Now you're getting there.  The simple way to do it is as follows -

 

1. Signal your line with 3 aspect or 2 aspect colour light signals auotmatically operated by passing trains except where you need to control them to red for some reason.

 

2. The signal protecting the platform should be a controlled signal in any case - all trains must be brought to a stand at it before either

a. operating it to as proceed aspect if the platform is empty, or

b. operating the 'calling on' aspect (a white light would be suitable) to signal a train to the rear half of the platform while the advanced end is occupied.  The train may only work forward to the advanced end of the platform when the line is clear to the next signal in advance and the Driver receives authority to move from the person in charge of the platform.  The next signal in advance must be in clear sight of the platform.

 

Essentially you only need 2 aspect signals because speeds are low and (hopefully) signal sighting will not prevent a problem.  But 3 aspect would be quite ok if you're prepared to pay the extra for them.

 

I have no doubt at all that the above would be acceptable to your insurers but you - as a society - must ensure that persons who will take charge of the platform are properly trained and that training records are maintained (and for Drivers).  As an additional safeguard the signal protecting the platform could be arranged to normally stand at red and a treadle or track circuit be operated (with timer if necessary) to allow it to be cleared to either of the proceed aspects in order to ensure that an approaching train is stopped before getting a proceed signal.

 

(n.b. no charge for the above proposal)

 

I'm curious. Why have trains come to a stand before proceeding to the platform if there isn't a train there? 

 

Something else I've wondered about - on the regular railway, when a train is worked permissively into an occupied platform line with the only "marker" being the tail lights of the train that's already there, is it a requirement that the train already there remains stationary until the train behind has stopped?

 

Somehow having one train following another doesn't seem too good an idea - they don't have brake lights. (Though I don't know how you'd prevent this from happening, and I think I've seen it 20 years or so ago in the UK).

[Coryton]

This is easy, when track circuits in the platform, show "not occupied" ie no trains berthed, the signal interlocking allows a non-danger proceed aspect, single yellow or less restrictive.

 

If the platform is occupied and the track circuits allow,  the signal will be a call on, two white lights and a danger  main aspect, the driver can proceed on the authority of the two whites and pass the main aspect at danger, driver must proceed with caution, prepared to stop at least 6 feet from the train berthed ahead.  This is PP permissive passenger working. There is also PG, permissive goods, same thing allowing freight trains into sidings.  Additionally when PP is allowed, (it is shown in the Sectional Appendix track diagrams)  normally, goods trains cannot enter a platform occupied by passenger stock,  the Driver of the goods train will contact the Signaller for verbal authority for the movement

 

Is it (still?) the case that some platforms are approved for permissive working only at times of disruption? 

[stadman]

Just a simple yellow aspect prior to platform if empty to permit train to enter. Second train comes in on a subsidiary signal such as the white dots at 35 Deg's similar to current practice. Fist driver knows where to stop by way of route knowledge, second is coming in on permissive and expects to find line occupied ( proceed towards next signal, bufferstop preparing to stop short of any obstruction and obey another signal)

Q. Why does the first train have to stop short to unload and proceed further along platform empty, why not just go right to end  / limit?

Kev S

[tender]

 

Q. Why does the first train have to stop short to unload and proceed further along platform empty, why not just go right to end  / limit?

Kev S

Hi Kev.

This is a 5" gauge miniature railway which has public running days. There will be separate set down and pick up parts of the platform to keep the public under control and hopefully avoid congestion  (free for all).

[The Stationmaster]

I'm curious. Why have trains come to a stand before proceeding to the platform if there isn't a train there? 

 

Something else I've wondered about - on the regular railway, when a train is worked permissively into an occupied platform line with the only "marker" being the tail lights of the train that's already there, is it a requirement that the train already there remains stationary until the train behind has stopped?

 

Somehow having one train following another doesn't seem too good an idea - they don't have brake lights. (Though I don't know how you'd prevent this from happening, and I think I've seen it 20 years or so ago in the UK).

Simples  - the best way to enforce any operational discipline is to make it as simple and consistent as possible.  The fact that trains will always be stopped will encourage everyone to regard that as the normal way of working.  If on the other hand you don't stop one but do stop the other confusion starts to creep in.

 

Don't forget that here we are talking miniature railway - still a passenger carrying line but hardly Network rail territory and therefore you start by adopting any principles to suit what you are dealing with rather than any slavish copying of the way things are done on 'the big railway' (in fact that is probably one of the worst things you could do).  Thus in this situation - or indeed any other - the first thing you do is risk assess it and that you try to introduce something in which any risks are ALARP (As Low As Reasonably Practicable).  The given here is the need to have two strains at the platform at one time (but probably not every time). the risk are reasonably straightforward (principally collision between trains but even more importantly in terms of frequency) risk to people joining or alighting the first train when the second one enters the platform.

 

So get the thing ALARP you do whatever you can to minimise risk potential.  Stopping every train becomes a standard procedure which won't be overlooked if someone gets confused (they do) because it's what they always do, a train starting from a stand is going to have less kinetic energy than one which comes sailing past a signal that has been cleared in advance for it so another potential risk is mitigated.  Effectively a miniature railway train is being driven on sight but interposing a signal with a clear and obvious instruction to stop is a worthwhile reminder where additional risk potential exists.