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The Token System

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spoony

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Sorry if this is in the wrong area but Im a newbie here, but can somebody please explain it too me in laymans terms. I was recently traveling on the Esk Valley line from Middlesborough to Whitby which is single track. every so often there would be a sign saying stop, gain token before advancing or something to that effect. Now from what I can gather its to stop more than one train being on the same stretch of track at once. Ive done some research into it but am still none the wiser as to how it actually works. Thanks in advance if someone could explain it for me:grin:
 
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morgantyreman

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Single line working from Nunthorpe mate, only one train is supose to be on the line at one time but tokens mean it is possible for more that one. I.e A local can travel from Gromont to Middlesbrough the same time a Steam is running the same
 

Muttley

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Theres a token machine at each end of the line. The machines are connected electrically so that you must have release given by the other end to release your token. Once a token has been released from either machine then BOTH machines are locked. The token must be returned to either end before another is released from either end.

Thats the basics.

You can augment things by locking the starting signal with the token machine, breaking long sections up with more token sections, doing away with one of the signallers (as on your branch), etc, etc.

As ever, the true nitty gritty comes when the system fails.

Hope that helps.
 

spoony

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Theres a token machine at each end of the line. The machines are connected electrically so that you must have release given by the other end to release your token. Once a token has been released from either machine then BOTH machines are locked. The token must be returned to either end before another is released from either end.

Thats the basics.

You can augment things by locking the starting signal with the token machine, breaking long sections up with more token sections, doing away with one of the signallers (as on your branch), etc, etc.

As ever, the true nitty gritty comes when the system fails.

Hope that helps.

Cheers, I was as clear as mud before but that makes a bit more sense:D
 

TheSlash

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Dan, i'm a part time signalman and i was confussed after reading the report into the Aylesbury incident!
You complicate things even more with staff and ticket, pilotman working etc :grin:
 

dan_atki

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:oops: My apologies to anyone who's finished more confused than they started.

I think, though, that the quick rundown in the appendix on page 28 is a good description for someone who has no idea whatsoever about the system.
 

CosherB

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What happens if you have a lot of trains all going the same way along the single line stretch, one after the other. Each will take token from one machine, and return it to the other machine on exiting the section. Eventually, unless a train uses the section the other way bringing a token back, the first machine will run out of tokens.

Does this ever happen?

CS
 

Muttley

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What happens if you have a lot of trains all going the same way along the single line stretch, one after the other. Each will take token from one machine, and return it to the other machine on exiting the section. Eventually, unless a train uses the section the other way bringing a token back, the first machine will run out of tokens.

Does this ever happen?

CS


Over the course of days or weeks this can happen. Our local token machines start with 10 a piece, but theres one train more a day on the Up line. So on average they`ll need to be an equalling out around once a week.
The local S&T come out and have to disconnect the system, remove a handful of tokens, and van them to the other end-never by train.

Naturally this occurs at a convenient time (ha ha) and theres never a problem reconnecting 100yr old bits of kit.:?
 

Oracle

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On the North Norfolk Railway it was 'One engine in steam', for diesel or steam when I was learning to drive on the line. You had to pick up the token at the start of the section and then hand it back. A loco driver forgot to collect the token and ended up at the end of the line. He was then told to stay where he was and a ticket was sent to authorise him to return. He was suspended for a time.
 

33056

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Mutley, they shouldn't need to disconnect the system - there is an implement to do this (not sure of it's correct name!)

yu5g3s.jpg


Seen here between two token machines at Welshpool in 1980.

Here are two pictures of the equipment in position on the Central Wales line

ymbvuk.jpg


ymbvul.jpg
 

TheSlash

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I've never seen a token machine like that before, normally the S&T just take the front off or something.
 

Tomnick

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On the North Norfolk Railway it was 'One engine in steam', for diesel or steam when I was learning to drive on the line. You had to pick up the token at the start of the section and then hand it back. A loco driver forgot to collect the token and ended up at the end of the line. He was then told to stay where he was and a ticket was sent to authorise him to return. He was suspended for a time.
The North Norfolk's ETB between Sheringham and Weybourne, which is as previously described (a number of tablets in instruments at either end of the section, from which only one tablet can be 'out' at any one time). Beyond Weybourne, it's 'one engine in steam' (currently, anyway) to Holt, so there's only one staff, which must be returned to Weybourne before a second train can leave for Holt.

There's a further complication in that Weybourne can 'switch out', in which case the long section extends right from Sheringham to Holt, again worked 'one engine in steam' with a single staff.

A look at the relevant modules of the online rulebook might be of some use - TS4 and TS8.
 

AlexS

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Dan, i'm a part time signalman and i was confussed after reading the report into the Aylesbury incident!
You complicate things even more with staff and ticket, pilotman working etc :grin:

The Aylesbury incident was interesting because of the confusion in communication - useful system though where you can lock trains in loops within the section with intermediate token machines, providing it's all used properly!
 

Sir_Clagalot

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I think the Esk Valley Line is RETB (Radio Electronic Token Block). Did the signs have a light at the bottom that was steady blue until the token had been recieved, then it starts flashing. Same as the West Highland and Far North/Kyle lines in Scotland.
 

Metroland

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Esk Valley line is definitely No signalman token, fitted in the late 1980s to save money. It works as described by drivers taking out tokens from locked token machines, I believe the signalling connection actually runs across BT telephone lines.

The old system is seen here for the last time.

http://www.youtube.com/watch?v=BX01NnAQGfc

[youtube]BX01NnAQGfc[/youtube]
 

Death

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Hail All! <D
I'm glad that Spoony started this thread...Although I've always had a very basic understanding of how a railway token system would work (As it's similar in principle to communication management on a token-ring LAN), I've always wanted to learn about the system in depth...And the linked PDFs and YT videos have given me all the info that I could ask for! 8)
(Until this thread came up, I hadn't been able to find a suitable resource for my perusal anywhere. Even using every single trick in the Google Hackers book, I could only find documents on coin-op electricity meters etc... :shock::sad:)

I do have a few questions about token block related things though, if I may:
  1. As a white-hat hacker (One who knows all about dodgy computer skills, but never uses them for ill. :)) I do wonder if the Radio-Electronic Token Block (RETB) system is secure. Although the original token system (The 1900CE one with whopping Iron "tokens!") is - By it's very nature - 99.666% secure and fail-safe, an RETB token could - In theory - Be passively recorded as it was passed from the signalbox to the train, and someone attempting to perform a MiM (Man in the Middle) attack could wait for a short while and then spoof a "Returning the token" communication as if it had originated from the trains token device! :shock:
    Now, I would hope that such a safety-critical train access and control system would make use of very strongly encrypted and digitally signed communications for token passing...But the question I really have to ask - And I'd like an honest answer - Is: Are they? ;)
    .
  2. Although I havn't used that stretch of line for a good 6+ months or longer, I've never noticed any token devices, RETB boundary markers, or permanent red signals on the line between Ash Vale and Frimley. Given that a good 4-6 miles of this line is bi-directional single road, how come there isn't an apparent token system in use there? :)
    .
  3. Although I can understand that the token system is more designed for slow and twisted branch lines, could RETB accept and return tokens whilst the vehicle carrying the token is in motion at higher speeds - Maybe 125mph and over? 8)
    (If not, that must be a right pain in the dérriere for FGW, AXC and NXEC if they have to divert down obscure branch lines and still keep to timetable... :shock:)
Farewell...And thanks for the info! <D
>> Death <<
 
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Tomnick

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I can't answer your first question, I'm afraid, but I'd be pretty certain that it's rather secure. Even if someone did somehow manage to 'get in', the fact that verbal communication is required to request/surrender tokens would make any such attempt look a little suspicious.

Now then, second question! There's a couple of methods of working single lines that don't involve a token, physical or 'radio'. Probably the most common is track circuit block, where - unsurprisingly - track circuits are used to prove the absence of trains on the single line, and protecting signals are interlocked with these, each other, and, sometimes, direction/acceptance levers/switches or some other way of giving a 'slot'. Look at Simsig for a few examples. Another is tokenless block, which is explained quite thoroughly in that link to the relevant rulebook module.

I'm not sure about the idea of exchanging tokens at speed - for a start, I'm not sure about the politics of 'carrying' a 'token' beyond the end of the single line section in question, which is a big no-no on electric token block lines. There's also the issue of communicating with the signalman, and exchanging tokens, whilst on the move - not sure how practical that'd be. Given the relatively low linespeeds, I'm not sure that stopping would be such an issue, and the time taken to exchange tokens would certainly be allowed for.
 

Craig

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I think the Esk Valley Line is RETB (Radio Electronic Token Block).

Unless it's changed recently the Esk Valley uses the traditional token keys system. The line is controlled from Nunthorpe signal box and there are token machines at Battersby and Glaisdale. There are also arrangements in place for movements to/from the NYMR at Grosmont, I believe someone from Network Rail comes with a token and operates the ground frame.
 

Tomnick

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I believe that there's additional 'intermediate' token instruments at Grosmont and Whitby, so a token can be released at either to allow a train out onto the single line, and equally a train can be shut inside at Whitby to allow a unit to run from Glaisdale to Whitby and back. I seem to remember (from my own observations) that it's possible to stand a unit at the buffer stops (clear of an 'end of single line' notice) at Whitby and surrender the token - believe there is/was something in the Sectional Appendix advising drivers to be prepared to find a unit standing at the stops.
 

AlexS

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There's definately a token machine at Grosmont because I've seen it :lol: Hidden in a standard grey loc cabinet, standard surprisingly ornate annetts key design. We had a GCR S&T visit to the Moors and the whole set up at Grosmont is quite interesting.
 

Death

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Hail again! <D
I can't answer your first question, I'm afraid, but I'd be pretty certain that it's rather secure. Even if someone did somehow manage to 'get in', the fact that verbal communication is required to request/surrender tokens would make any such attempt look a little suspicious.
Ahh...I was given the impression that when a token is passed over a RETB system, the relevant signaller(s) would hold in the release buttons on their appliances causing a "token available" communication to be displayed on the appliances of all trains in the vicinity, with the driver of the relevant train then holding in the "Accept" button on their appliance to take ownership of the token without the need for additional voice communication. 8)

Incidentally...Does RETB use it's own radio frequencies, or does it work using standard communication bands such as those used for CSR? :)

Now then, second question! There's a couple of methods of working single lines that don't involve a token, physical or 'radio'. Probably the most common is track circuit block, where - unsurprisingly - track circuits are used to prove the absence of trains on the single line, and protecting signals are interlocked with these, each other, and, sometimes, direction/acceptance levers/switches or some other way of giving a 'slot'. Look at Simsig for a few examples. Another is tokenless block, which is explained quite thoroughly in that link to the relevant rulebook module.
Hmmm...Just after I made that previous post, it occured to me that - With the section being pretty short and having no diverging paths or loops along it's length - The signalling system would only need to display a red at both ends (I.E: Only one train permitted in the section at any time in any direction) whenever the block is occupied...Meaning that the train itself would act as a whopping great "token" in it's own right! :lol:
Of course, this assumes that the section is actually controlled using the "one train only" principle. I suppose (R)ETB or a similar system would be provided if the section needed to be capable of accommodating multiple trains travelling in the same direction at the same time - But given the block length, this probabally isn't necessary. :)

I can't believe that I was so tired this morning that I forgot about the existance of standard track circuit signalling though... :shock::roll::razz:

I'm not sure about the idea of exchanging tokens at speed - for a start, I'm not sure about the politics of 'carrying' a 'token' beyond the end of the single line section in question, which is a big no-no on electric token block lines. There's also the issue of communicating with the signalman, and exchanging tokens, whilst on the move - not sure how practical that'd be. Given the relatively low linespeeds, I'm not sure that stopping would be such an issue, and the time taken to exchange tokens would certainly be allowed for.
Hmmm...Well, my idea on this point was aimed entirely towards the RETB system (Could ye imagine trying to obtain/hand-over a physical token at 125mph? :lol:) but the following is kind of what was going through my mind when I asked that question. For this, assume that ye have a Voyager approaching a RETB controlled section at 125mph, and that it will maintain that same speed throughout unless instructed otherwise: :)
  1. As soon as the train enters the relevant signalling region, it's presence is acknowleged by the signaller for that section who informs the driver and other relevant signallers that a "rolling token handover" will be performed. At this point, the train in question is still about ten miles from the start of the RETB section.
  2. Token availability is checked across the system, and if the token is currently available then agreement is sought with all signalmen and the token is reserved for the Voyager's use. If the token is not available at that time (I.E: Another train already possesses it) then the driver of the Voyager is informed and instructed to halt at the start of the RETB section. In such a case, standard token procedure would be used insted.
  3. Once the token is reserved for the Voyagers use and as soon as the train has entered the transmission area of the RETB system, all signallers and the trains driver hold in the relevant buttons to hand possession of the token to the Voyager.
    At this point the Voyager might still be about 3-5 miles from the start of the RETB controlled area, but - Already having possession of the token - It would effectively be "pre-cleared" for entering the section.
  4. The Voyager flies into and through the RETB controlled section at maximum line speeds, preferably already being pre-cleared for the entire RETB controlled section of network allowing direct end-to-end travel.
    (If second and subsequent RETB sections exist after the first one, all necessary tokens for the train would be reserved and sent out at the same time as the first one. Otherwise, the driver is informed as to which section(s) he can "fly" through on entering the first section, after which he'd stop the train at the end of the section and obtain additional tokens as normal.)
  5. Upon exiting a section (And not before) the driver would inform the relevant signallers that he is clear of the section, and release the token as normal without stopping the train. As RETB uses virtual tokens passed across radio, no physical handover is required - Meaning that theoretically it is not necessary to stop a train to obtain or return a token that is carried upon it. :)
Although one possible flaw that has just come to my mind with regards the RETB system - Though it would have to be committed by human error - Is that as no physical tokens are used, a token could (In theory) be released by a driver before he has actually exited a section if he wanted to try and speed things up. Obviously if such a thing were to happen (Perish the thought!) the token could be handed to another train that is about to travel down the same line in the opposite direction, with potentially unfortunate consequences occurring when both trains encountered each other! :shock:

Two additional RETB questions that I now have though, if I may: 8)
  1. Looking at one of the linked PDFs (Concerning a near miss in the vicinity of Aylesbury) it becomes apparent that physical tokens are also used as keys to unlock ground frames and other manually controlled loop arrangements, effectively handing possession of the token to that loop and any train upon it.
    Now as a traditional ETB system makes use of physical tokens that can double-up as frame keys, this is a simple way of safely "locking out" an entire single-line section to allow for locomotive movements to take place. Is the same principle used in RETB systems (Perhaps with a token-holding appliance that will only unlock the ground frame once it has obtained the token), or are these supplimented with a physical frame key? :)
  2. What would happen in the event of a token appliance experiencing a critical failure of some description whilst it was in possession of the token, meaning that the token for that section of line would effectively be lost? :shock:

Farewell... <D
>> Death <<
 

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Tomnick

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Hail again! <D Ahh...I was given the impression that when a token is passed over a RETB system, the relevant signaller(s) would hold in the release buttons on their appliances causing a "token available" communication to be displayed on the appliances of all trains in the vicinity, with the driver of the relevant train then holding in the "Accept" button on their appliance to take ownership of the token without the need for additional voice communication. 8)

Incidentally...Does RETB use it's own radio frequencies, or does it work using standard communication bands such as those used for CSR? :)
Once again, no certainty in my knowledge of RETB, but it's my understanding that the signalman issues the token specifically to the intended train; the token then being transferred by driver and signalman simulataneously pressing their relevant button. The request for the token and confirmation of receipt are carried out verbally, as are one or two other bits and pieces ("clear of loop" being one that springs to mind)

Hmmm...Just after I made that previous post, it occured to me that - With the section being pretty short and having no diverging paths or loops along it's length - The signalling system would only need to display a red at both ends (I.E: Only one train permitted in the section at any time in any direction) whenever the block is occupied...Meaning that the train itself would act as a whopping great "token" in it's own right! :lol:
Of course, this assumes that the section is actually controlled using the "one train only" principle. I suppose (R)ETB or a similar system would be provided if the section needed to be capable of accommodating multiple trains travelling in the same direction at the same time - But given the block length, this probabally isn't necessary. :)
If there are intermediate signals, then there's no reason why more than one train can't be on the single line at once. There'll be additional controls to make sure that everything's travelling in the same direction (i.e. once one train is allowed into the section in the Up direction, the protecting signal can't be cleared for a Down train), and the function of ensuring that the trains are kept a safe distance apart will be carried out by the intermediate signals. See Waterloo Simsig for this in action - set a route along the Windsor Reversible and note how all the automatic signals come 'off' all at once, and how you will be prevented from setting a route onto the line in the opposite direction.

It's also possible with ETB - Berney Arms (between Reedham and Yarmouth) had a box to break the section. When it was open, there was a token section either side, but no passing loop. Whether there were controls to prevent the signalman to accept a train from both the Yarmouth end and the Reedham end at the same time, or whether it was left to the signalman's common sense, I don't know!

I suppose the same thing would be possible with RETB, but I don't know whether it's actually been implemented anywhere. There's one or two isolated stop boards that I can think of - I believe there's one approaching Crianlarich from both Oban and Fort William, for example - but these are to permit trains to approach Crianlarich from the loop in rear whilst the junction is still blocked by a conflicting move. In that case, the authority would be to proceed only as far as the intermediate stop board, where a further token would be required. A 'long section' token would be issued at the loop in rear if the authority to proceed was right into Crianlarich station, in which case there'd be no need to stop at the intermediate stop board.

Hmmm...Well, my idea on this point was aimed entirely towards the RETB system (Could ye imagine trying to obtain/hand-over a physical token at 125mph? :lol:) but the following is kind of what was going through my mind when I asked that question. For this, assume that ye have a Voyager approaching a RETB controlled section at 125mph, and that it will maintain that same speed throughout unless instructed otherwise: :)
I think I can say with almost complete certainty that any such line would either be doubled or track-circuited throughout! RETB was introduced as a method of signalling to reduce costs on a few marginal lines, so is only really suited to those lines with a sparse service and low speeds.

...Although one possible flaw that has just come to my mind with regards the RETB system - Though it would have to be committed by human error - Is that as no physical tokens are used, a token could (In theory) be released by a driver before he has actually exited a section if he wanted to try and speed things up. Obviously if such a thing were to happen (Perish the thought!) the token could be handed to another train that is about to travel down the same line in the opposite direction, with potentially unfortunate consequences occurring when both trains encountered each other! :shock:
I suppose that's entirely possible, and it's these little flaws that make it unsuitable for anything other than a line with a few trains a day, pootling up and down at a nice leisurely pace! Given that all communication is 'open' (so can be heard by drivers of other trains), I'd expect the driver of a train waiting at loop A would be most surprised to hear the driver of another train claiming to have just arrived there and cleared the single line!

Two additional RETB questions that I now have though, if I may: 8)
  1. Looking at one of the linked PDFs (Concerning a near miss in the vicinity of Aylesbury) it becomes apparent that physical tokens are also used as keys to unlock ground frames and other manually controlled loop arrangements, effectively handing possession of the token to that loop and any train upon it.
    Now as a traditional ETB system makes use of physical tokens that can double-up as frame keys, this is a simple way of safely "locking out" an entire single-line section to allow for locomotive movements to take place. Is the same principle used in RETB systems (Perhaps with a token-holding appliance that will only unlock the ground frame once it has obtained the token), or are these supplimented with a physical frame key? :)
  2. What would happen in the event of a token appliance experiencing a critical failure of some description whilst it was in possession of the token, meaning that the token for that section of line would effectively be lost? :shock:
The arrangement at Aylesbury (and Glaisdale/Grosmont/Whitby a couple of posts ago) does indeed allow a token to be released for shunting on the single line at an intermediate point. It also allows trains to be 'shut inside' for other traffic to pass, perhaps while they shunt, and then to obtain another token to continue their journey on the single line. I don't see why that would be impossible with RETB...I just don't know if it's done! It's certainly possible to obtain shunt and engineers tokens (to shunt at a passing loop and to take possession of an single line section for engineering purposes) - if the worst comes to the worst, and it's possible for the system to 'lose' that token, then the signalman should still have a record of its issue?

Phew! What a post ;)

I've just found this, which may be of some interest. I knew there was an article somewhere, but I couldn't find it. Wish I'd found it before I typed all that out :)

Tom
 

Craig

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I seem to remember (from my own observations) that it's possible to stand a unit at the buffer stops (clear of an 'end of single line' notice) at Whitby and surrender the token - believe there is/was something in the Sectional Appendix advising drivers to be prepared to find a unit standing at the stops.

There's also a siding and run round loop at Whitby which trains can be locked in to. I've seen this happen a couple of times with stock from railtours.

I think the situation you've described above with two units in the station happens on a Sunday.
 

Max

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There's also a siding and run round loop at Whitby which trains can be locked in to. I've seen this happen a couple of times with stock from railtours.

I think the situation you've described above with two units in the station happens on a Sunday.

As far as I know, there there is no scheduled working where 2 units are in Whitby at the same time. On summer Sundays, units do pass each other at Glaisdale, but this doesn't happen on any other days, except when the NYMR operate special Whitby-Battersby trains, which sometimes happens on gala events. There was one Sunday before the summer timetable started when two NYMR services operated between Whitby and Battersby and passed at Glaisdale, the first time two steam trains have passed on the line for many years.
 

Craig

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As far as I know, there there is no scheduled working where 2 units are in Whitby at the same time.

The current timetable shows arrivals at Whitby at 10:14, 11:18, 12:33, 15:44 and 16:58 with departures at 10:24, 12:43, 15:57, 17:20 and 18:00. The times would suggest that the 18:00 is formed by the 11:18 arrival?
 

Muttley

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STOP

A single line operating under ANY signalling system will be ONE BLOCK SECTION for its entirety. There will be NO block signals along its length.

Why ?

Because if theres block sections theres nothing to stop a train entering from both ends. OK, they might not hit head on due to the blocks, but they can`t pass each other-think of that photo of the railways across the USA meeting for the first time.

But I`ve seen signals on a single line.

There`ll be non-block signals for level crossings. As they`re non-block signals they don`t affect the amount of trains running.

As to passing tokens at speed, the S&D had it perfected on their section of line with various ex-SR and BR Standards with `catching` equipment on the cab sides. This also carried on to the diesels, with many classes so fitted. They all had the equipment removed and plates welded over the recesses in the `70s.
 

Tomnick

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There's definitely several examples of single-line sections with signals (not non-block signals) 'breaking the section'. In most cases (such as my earlier example of the Waterloo Reversible - try it in Simsig!), there's controls to prevent the situation of two trains meeting each other - once one train has been signalled in one direction, the line is then 'locked' in that direction until it's clear throughout once again.

There are also locations where there's no such controls (Pyewipe Junction, on the 'Light Railway' between Immingham and Grimsby, for example) - the diagram shows the layout , and it's definitely a block post as it's key token towards Immingham and TCB towards Grimsby! I'm certain that there's nothing here to prevent one being accepted from both directions at once.
 

Death

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Why? I obtained the token for this stretch of line just two minutes ago! :lol::razz:8)

Because if theres block sections theres nothing to stop a train entering from both ends. OK, they might not hit head on due to the blocks, but they can`t pass each other-think of that photo of the railways across the USA meeting for the first time.
That reminds me of that dappy old railway rule that AFAIK still exists in certain US states - The rule that If two trains should meet face to face, then both shall stop and neither shall start up again until the other has gone. :shock::roll::D

As to passing tokens at speed, the S&D had it perfected on their section of line with various ex-SR and BR Standards with `catching` equipment on the cab sides. This also carried on to the diesels, with many classes so fitted. They all had the equipment removed and plates welded over the recesses in the `70s.
Hmmm...So much for the additional benefit of RETB then, assuming that your statement refers to the traditional, physical tokens! 8)

Mind ye...I'm rather perplexed as to why they'd remove such a system from the trains when it could still be put to good use in sections where RETB hasn't been installed yet. Was that another of Dr. Beeching's so-called "good" ideas (<(), or was it just a case of too many dropped tokens? :)

Farewell... <D
>> Death <<
 
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