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Information please on Scottish Tokenless Block working


imt

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I am looking at creating a fictitious layout in Scotland - late 1960s.  The line is the one never built to Ullapool and beyond.  I think it would have been worked using Tokenless Block and I am seeking relevant diagrams and paperwork to understand how it would work and what traffic throughput might be achieved.  I believe that Tokenless Block was created to allow denser traffic by reducing the manual intervention of token exchange and so on.

 

I know this is all ancient history now with RETB but are there some older signalmen (or should that be signallers?) out there with any recollections?

 

I have found the following document on the web which is most helpful - if technically about a Western implementation:


But I am having great difficulty finding anything else.  I also have a copy of the BR Regulations for the Tokenless Block System 1968.

 

Really what I need more than these documents is some practical advice on how it all actually worked.

 

I have appended a diagram to assist in making comments

 

Questions:

1. It seems that the system enforced that a train on the line between passing loops/stations would not have a second train following on - as might have been achieved with staff/ticket working. The process followed seems to enforce one train at a time whether the inter-station line was 5 miles or 50 miles long? Have I misunderstood?

2. There seems to be a requirement in the Regulations that passing trains must be held at the home signals, and then allowed into their appropriate side of the loop/platform one at a time when both are present and have come to a halt. One can see that signalmen cannot do everyting at once, and there are a series of actions that need to be taken for each train, but this approach does does seem to impose delays - an early train stands outside the station, and stands even longer if the opposite train is late (maybe passengers were more patient in the 60'?).  Why can the trains not be signalled into the appropriate side of the station/loop to come to a halt there? I know we don't want a head on clash, but they could be signalled in at caution, the points could be locked to prevent crossing onto the wrong line and traps/sand drags provided?

3. Some trains are passing through without a train coming in the opposite direction, and may not even need to stop (a passing freight for example. Is it possible to "offer on" a train you have not yet got or would the control logic prevent it? i.e. do the sequential TCs and treadle need to be operated on the incoming line before the "offer" forward can be made?

4. The system is supposed to allow attendantless operation in some ways (like keeping the commutator at "accept") but as far as I can see, unless the box is switched out the "Train arrived" button must be depressed in order for the locks to be released. Am I right? And anyway points and then signals would need to be replaced normal.

 

Thank you to those who have had the patience to read thus far.

 

Any comments, corrections, document references etc. would be gratefully received.

 

post-14883-0-38152700-1468770489.jpg

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From the modelling perspective it looks exactly the same Electric Token, and the signals are in the same place just there is no token as the work is done by a direction lever in the box plus the signalman at either end visually checking that the train is complete through section or getting an assurance that this is so!

 

Mark Saunders

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Hi imt

 

You need to be a bit cautious here, the document on the web re the WR/BRB tokenless block has little or no bearing on the way the ScR version worked. They are different animals. Essentially it functioned electrically the same as a key token or electric tablet machine without the physical key or tablet and indeed passage of trains were recognised by a mixture of track circuits and treadles, although normal visual observation by the signalman was required as well. There are some tokenles sections still in operation, notably Stanley Junction (Perth) to Aviemore.

 

The basic principal of block signalling is that a section will have only one train in it. This applies whether its staff and ticket or any other single line control system.

 

Admission of trains to crossing loops was done so that in the advent of a one train not stopping the collision would be head on rather than a potentially more injurios side swipe. Once you have sand drags at the end of loops the trains can be admiited from both ends simultaneously.

 

Tokenless block operates in the same manner as any other, you can offer a train forward at any time you wish, it doesn't have to arrive first.

 

The attendantless bit is peculiar to the WR system, it doesn't apply to the ScR system.

 

A most interesting document is published by the Signalling Record Society on the ScR tokenless block system, it's pretty technical but will tell you all you need to know.

 

 

Mark

 

Single line working by direction or acceptance lever is by definition tokenless but isn't really tokenless block, its rather more a variant of TCB.

 

Hope this is helpful

Regards

Martin

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[quote name="Martin Shaw" post="2371928"

 

Mark

 

Single line working by direction or acceptance lever is by definition tokenless but isn't really tokenless block, its rather more a variant of TCB.

 

Hope this is helpful

Regards

Martin

 

Martin

 

I only go off the Sectional Appendix rather than the technical, it is the same as "axle counters" being shown as TCB when the technical side is different!

 

Mark

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You need to be a bit cautious here, the document on the web re the WR/BRB tokenless block has little or no bearing on the way the ScR version worked. They are different animals. Essentially it functioned electrically the same as a key token or electric tablet machine without the physical key or tablet and indeed passage of trains were recognised by a mixture of track circuits and treadles, although normal visual observation by the signalman was required as well. There are some tokenles sections still in operation, notably Stanley Junction (Perth) to Aviemore.

 

The basic principal of block signalling is that a section will have only one train in it. This applies whether its staff and ticket or any other single line control system.

 

Admission of trains to crossing loops was done so that in the advent of a one train not stopping the collision would be head on rather than a potentially more injurios side swipe. Once you have sand drags at the end of loops the trains can be admiited from both ends simultaneously.

 

Tokenless block operates in the same manner as any other, you can offer a train forward at any time you wish, it doesn't have to arrive first.

 

The attendantless bit is peculiar to the WR system, it doesn't apply to the ScR system.

 

A most interesting document is published by the Signalling Record Society on the ScR tokenless block system, it's pretty technical but will tell you all you need to know.

 

 

Thank you so much for your informative reply.

 

I was beginning to understand that the WR and ScR TB systems were different animals.  What I'd love for you to do if you can is point me to something I might understand about the ScR version that is digestible like the WR write up is. The SRS paper I have seen and I am still reeling from its content.  To rephrase Eric, I understood all the words - but not in that order!

 

I understood the bit about TCs and treadles and your reassurance that with more protection available trains could be signalled direct into stations is helpful.  I am not sure whether coloured light signals are necessary, the BR write up does describe semaphore operation too.

 

Sorry to have been stupid, I had been told many times about block signalling and it should have stuck but it didn't. I don't suppose my line would have been MAS signalled, but could trains have followed each other between signal boxes in that case?  I really doubt that BR would have funded extra passing loops and signallers either, so there would be built in limitations on how many trains could be timetabled.

 

However how does the idea of seeing the token and taking a ticket work if you have to wait until the token is in the machine at the other end - why have the ticket?  In my ignorance I thought the second train followed the first some time afterwards driving at caution.  I can see that my idea is fraught with danger.  What were tickets for?

 

Thanks again.

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Tickets are used with train staffs, rather than with tokens. The staff is carried by the *last* train to travel in a given direction. Previous trains are shown the staff and given a ticket; the signalman at the other end has to have received the ticket before he can give the Out Of Section bell signal.

 

(A pedant would point out that even in a token block section you can still have tickets - when pilotman working has been introduced - but that is a bit of a pedantic complication!)

 

With any of these forms of working - staff and ticket, token, or tokenless - you can still only have one train in section (i.e. between signalboxes) at once, even if they are travelling in the same direction. All can be used with semaphore signals. Also, because there is only one train in section, all trains can travel at the maximum speed otherwise allowed - your hypothetical "the second train follows under caution" does not apply.

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you can still only have one train in section (i.e. between signalboxes) at once, even if they are travelling in the same direction.

 

<pedant>

 

Depends on the signalling - between Acle and Great Yarmouth (tokenless block) there were automatic signals on the single line - increasing capacity by allowing trains to follow one another down the single line.

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You can also have tickets with Tokenless Block, at least with the WR version. I'd think it (at least in principle) matches what would happen in Scotland.

 

In the event of a block failure, the signaller wishing to send the next train (Signaller A), contacts his on-call manager, explaining the situation and requesting authority. The on-call manager then contacts the signaller at the other end of the single line section (Signaller B) to verify that all previous trains have passed complete. Once satisfied, the manager authorizes Signaller A to pass the next train under Modified Block Working. Signaller advises the driver of the circumstances and action to be taken and issues a ticket listing what he/she is required to do, i.e. Pass signal X at danger, obey all others and surrender the ticket to Signaller at B.

 

This arrangement is used to prevent delays being incurred awaiting a Pilotman - by the very nature of lines so signalled, a suitable person isn't likely to be located exactly on the doorstep! 

 

John

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I am looking at creating a fictitious layout in Scotland - late 1960s.  The line is the one never built to Ullapool and beyond.  I think it would have been worked using Tokenless Block and I am seeking relevant diagrams and paperwork to understand how it would work and what traffic throughput might be achieved.  I believe that Tokenless Block was created to allow denser traffic by reducing the manual intervention of token exchange and so on.
 
I know this is all ancient history now with RETB but are there some older signalmen (or should that be signallers?) out there with any recollections?
 
I have found the following document on the web which is most helpful - if technically about a Western implementation:
But I am having great difficulty finding anything else.  I also have a copy of the BR Regulations for the Tokenless Block System 1968.
 
Really what I need more than these documents is some practical advice on how it all actually worked.
 
I have appended a diagram to assist in making comments
 
Questions:
1. It seems that the system enforced that a train on the line between passing loops/stations would not have a second train following on - as might have been achieved with staff/ticket working. The process followed seems to enforce one train at a time whether the inter-station line was 5 miles or 50 miles long? Have I misunderstood?
2. There seems to be a requirement in the Regulations that passing trains must be held at the home signals, and then allowed into their appropriate side of the loop/platform one at a time when both are present and have come to a halt. One can see that signalmen cannot do everyting at once, and there are a series of actions that need to be taken for each train, but this approach does does seem to impose delays - an early train stands outside the station, and stands even longer if the opposite train is late (maybe passengers were more patient in the 60'?).  Why can the trains not be signalled into the appropriate side of the station/loop to come to a halt there? I know we don't want a head on clash, but they could be signalled in at caution, the points could be locked to prevent crossing onto the wrong line and traps/sand drags provided?
3. Some trains are passing through without a train coming in the opposite direction, and may not even need to stop (a passing freight for example. Is it possible to "offer on" a train you have not yet got or would the control logic prevent it? i.e. do the sequential TCs and treadle need to be operated on the incoming line before the "offer" forward can be made?
4. The system is supposed to allow attendantless operation in some ways (like keeping the commutator at "accept") but as far as I can see, unless the box is switched out the "Train arrived" button must be depressed in order for the locks to be released. Am I right? And anyway points and then signals would need to be replaced normal.
 
Thank you to those who have had the patience to read thus far.
 
Any comments, corrections, document references etc. would be gratefully received.
 

 

The procedure described in your Question 2, was not universal.

 

At Honiton (WR system) we had approach-controlled colour light signalling and were exempted from the rule requiring trains to be stopped at the Home signals.

 

At locations not so equipped, the phrase "when both (trains) are present" gives the clue. The purpose of stopping trains to be crossed is to ensure that they enter station limits slowly enough to be able to stop at the appropriate places, thereby avoiding any possible conflict at the other end of the loop (our Approach Control just automated the process).

 

When there is sufficient time to stop the first train, then get it "inside" and at a stand before the other approaches its own Home signal, that's exactly what happens, then the second train can be signalled through without being stopped. In practice, the first train would probably be "checked" rather than stopped at the Home signal, i.e. the signal would be cleared when the train had almost stopped. 

 

John

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<pedant>

 

Depends on the signalling - between Acle and Great Yarmouth (tokenless block) there were automatic signals on the single line - increasing capacity by allowing trains to follow one another down the single line.

 

Thanks for that information.  Not only does my line not exist (though it was planned) I am further off into the "lets pretend" by assuming oil /gas was found off the west coast, and this old single line suddenly had to take a lot more traffic.

 

I am trying to produce a "realistic" timetable, with trains crossing as appropriate.  Obviously the traffic that can be carried is heavily affected by crossing opportunities and the time taken  to do so, which is why I am interested in how BR handled these dilemmas.  It would be useful occasionally to send a freight after a faster passenger train without too long a wait.  Your point about extra "automatic" signals was what I was wondering about - so as to keep the trains safely separated on the long loop of nothing  between Dingwall and Garve for example.

 

Whether there would have been enough incentive to insert automatic signals would be an interesting thought.

 

Thanks very much for your help.

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The procedure described in your Question 2, was not universal.

 

At Honiton (WR system) we had approach-controlled colour light signalling and were exempted from the rule requiring trains to be stopped at the Home signals.

 

At locations not so equipped, the phrase "when both (trains) are present" gives the clue. The purpose of stopping trains to be crossed is to ensure that they enter station limits slowly enough to be able to stop at the appropriate places, thereby avoiding any possible conflict at the other end of the loop (our Approach Control just automated the process).

 

When there is sufficient time to stop the first train, then get it "inside" and at a stand before the other approaches its own Home signal, that's exactly what happens, then the second train can be signalled through without being stopped.

 

John

 

Thank you for that.

 

I was wondering about "approach control" - though I am not sure that it would have existed in the late 60's.  I had heard about it, and seen it working on our local Metro where main line and Metro trains run on the same track for a while.

 

The Regs. did seem very prescriptive - as of course they should be.  I thought practicality would overtake that but I wasn't sure how.

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Thank you for that.

 

I was wondering about "approach control" - though I am not sure that it would have existed in the late 60's.  I had heard about it, and seen it working on our local Metro where main line and Metro trains run on the same track for a while.

 

The Regs. did seem very prescriptive - as of course they should be.  I thought practicality would overtake that but I wasn't sure how.

But note that the inclusion of the phrase "when both are present" allows what I described when they aren't. No rules broken or even bent. In many cases, I'd think the WTT would have been designed to stagger arrivals to ensure the more efficient way of working.

 

The Approach Controls at Honiton dated from when the line was singled in 1967. The one on the (3-aspect) Up Loop Home was especially clever as it cleared to Yellow after 30 sec. if the Up Loop Starter was "On" but to Green after only 10 sec. once the Down train was in, the points reset, the accept obtained from Chard Junction for the Up to proceed and the Up Loop Starter had been cleared.

 

Interestingly, the 2-stage relay controlling it failed once and the only available spare one had to be sent down from Scotland whence the failed item was returned to replace it after repair. That suggests that at least one similar arrangement existed north of the Border.

 

All surprisingly sophisticated stuff for what were very much secondary routes.

 

John

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But note that the inclusion of the phrase "when both are present" allows what I described when they aren't. No rules broken or even bent. In many cases, I'd think the WTT would have been designed to stagger arrivals to ensure the more efficient way of working.

 

The Approach Controls at Honiton dated from when the line was singled in 1967. The one on the (3-aspect) Up Loop Home was especially clever as it cleared to Yellow after 30 sec. if the Up Loop Starter was "On" but to Green after only 10 sec. once the Down train was in, the points reset, the accept obtained from Chard Junction for the Up to proceed and the Up Loop Starter had been cleared.

 

Interestingly, the 2-stage relay controlling it failed once and the only available spare one had to be sent down from Scotland whence the failed item was returned to replace it after repair. That suggests that at least one similar arrangement existed north of the Border.

 

All surprisingly sophisticated stuff for what were very much secondary routes.

 

John

 

Thank you very much for sharing your knowledge and experience with me.  It's the kind of information which is unobtainable in any other way.  Thank you for your time.

 

As preparation for what I am doing, I laid my hands on some WTTs for the area - and they are (expensive) hen's teeth too.  Your point about the staggering of times I had unconsciously picked up from the WTTs (crossings on the Kyle line which are part of my area) so its built into my timetable already, but serendipitously.  I now understand WHY.

 

Pleased to see that colour lights were in use at the relevant time in Scotland, so I could do so prototypically.

 

Thanks again!

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Approach Control as far as I understand does not allow a signal to clear until the berthing track circuit has been occupied (and maybe timed) and is used as a form of speed control on approach to a crossover!

 

Mark Saunders

Also over 25mph points into a crossing loop. The timer is the crucial feature - the lower the speed restriction, the greater the delay. Approach to the signal in question followed a controlled distant which was also linked to the approach control for trains routed into the loop.

 

The dual-stage approach control was also linked to the block signal, clearance of which switched in the shorter delay. Many drivers would have seen the signal clear to yellow first then to green as the starter was cleared but, if the down train wasn't in, they'd only get the yellow. The 3-aspect Home thus doubled as a repeater for the Up Loop starter, sighting of which was round a curve with a footbridge (since replaced with a taller one in a different position) limiting the view.

 

It does seem rather a lot of complication to save what appears to be a maximum of 20 sec in running on a demoted route that the Western Region (at the time) had every intention of closing in the fullness of time after its singling. However, Honiton was something of a special case in that the approach controls were also incorporated to exempt the signalman from the requirement to stop trains on the homes and bring them in one at a time.

 

John

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Also over 25mph points into a crossing loop. The timer is the crucial feature - the lower the speed restriction, the greater the delay. The operation of Tokenless block relies on berthing track circuits being occupied and cleared in the correct sequence.

 

 

John

 

Thanks John, but I'm getting out of my depth.  Both you and Mark are now using terminology the average idiot does not understand - or at least this one doesn't!

 

"Berthing" track circuits, what are they where would they be placed and how do they differ from a track circuit?  I thought I understood a track circuit - a battery attached across the rails with train wheels making a circuit which could light lamps and feed relays.

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Thanks John, but I'm getting out of my depth.  Both you and Mark are now using terminology the average idiot does not understand - or at least this one doesn't!

 

"Berthing" track circuits, what are they where would they be placed and how do they differ from a track circuit?  I thought I understood a track circuit - a battery attached across the rails with train wheels making a circuit which could light lamps and feed relays.

Berthing Tracks Circuits are as the name suggests are there to prove when a train arrives at a Signal.

 

They also appear at Signals with a "white diamond" this is a reminder to the Signalman of the presence of a train rather than a Guard, Secondman or Driver going on the telephone to do this within two minutes!

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Berthing Tracks Circuits are as the name suggests are there to prove when a train arrives at a Signal.

 

They also appear at Signals with a "white diamond" this is a reminder to the Signalman of the presence of a train rather than a Guard, Secondman or Driver going on the telephone to do this within two minutes!

 

Please bear with me.  As I understand(?!) it, Tokenless Block requires a train to pass over 2 short TCs and operate a treadle both to prove its direction and physical arrival.  I had assumed the order TC1, Home sig., treadle, TC2 (though why I don't know).

 

I now understand that TC1 would be called a berthing TC - does that mean short as well?

 

Would there also be a TC at the platform/loop starter, or is that "TC2" in my description above.

 

What if the train were a fast passenger to be signalled through (after the train from the opposite direction is safely in the loop of course). Is that possible.

 

John's description of the Home signalling being 3 aspect and holding at yellow if the starter was at danger or green if a. the other train was safely in its loop and b. the starter had been cleared subsequent to acceptance by the box ahead.

 

Amy waving or drowning?

 

HELP!

 

(Edited to make clear I was referring to Tokenless Block working)

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  As I understand(?!) it, TCB requires a train to pass over 2 short TCs and operate a treadle both to prove its direction and physical arrival.  I had assumed the order TC1, Home sig., treadle, TC2 (though why I don't know).

Don't confuse TCB (Track Circuit Block) with Tokenless Block, which is the subject of this topic. TCB requires continuous train detection by track circuit or axle counter, Tokenless Block does not have continuous train detection hence the need for the direction checks etc.

Regards

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Don't confuse TCB (Track Circuit Block) with Tokenless Block, which is the subject of this topic. TCB requires continuous train detection by track circuit or axle counter, Tokenless Block does not have continuous train detection hence the need for the direction checks etc.

Regards

 

Being the idiot OP I hadn't - or I didn't think I had! Lost and astray in terminology as usual.  I WAS referring to Tokenless block and I have amended the post to make that clear. Sorry!

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