Doesn't explain the proper bell codes though

Thanks for the comment Tom, pleased to help with all things signalling!

Thanks for the comments and yes, as they say, nostalgia ain't what it used to be. Did they call it artificial intelligence? No. Is AI any smarter? Only as smart as the people using it is the history I think.

Thank you for your comment.. That is most interesting - do you have any pictures or video you could share? You can contact us through our web site www.sigbox.co.uk if you have files you can share . Thank you again

Yes, I have been watching a bunch of SRT videos as of recent, and came here looking for a good explanation in English on how this works.

thanks for the kind comments - much appreciated.

That is correct, that is the method of operation for single line track circuit block, and tokenless block. But without track circuits, these system do not work. How do you know if the train is clear of the single line, without track circuits?

​@@enochliu8316Good question, but in Italy, France and other countries there are still single track lines without track circuits. For example, here in Italy the lines are operated with the so-called "Single Manager" system, where circulation is based on telephone dispatches recorded between the agents (low-skilled, called underwriters) who attend the stations (known in Italian as "underwriters") and the "Single Manager" or between the "Train Manager" and the "Single Manager" in the case of a crossing or priority. In the "train" column of the service timetable, the locations where the train conductor is exempt from the so-called "countersignature" of the "Giunto" phonogram are indicated with a specific symbol. From these stations the train can depart without waiting for further formalities. Instead, if the appropriate symbol is not present in the "train" column of the service timetable, in order to order the train driver to depart, the train conductor must countersign the phonogram of the "Giunto" exchanged between the hirer and the Sole Manager. . This ensures that the route up to the next station where the countersignature of the "Joint" is expected is free. In any case, in the event of delays, the Sole Director can bind the departure of a train to the countersignature of the joint. In the event of a significant delay in one of the two crossing trains, the Sole Manager verbally transmits to the Train Conductor the text for completing the specific prescription to be drawn up on the appropriate form (Form M1, Crossing Movement Order). As you can read, neither in the stations nor along the single track sections between one station and another are there track circuits. The switches (points) are secured via FS type key switch stops whose keys are normally secured in a central lock whose "Control Key" (CC) is kept in a safe. Only the Sole Manager can authorize the removal of the Control Key from the safe. The sole manager communicates, via the same non-selective telephone circuit, also with the "Line Posts" which remotely close the level crossings via simple or double wire transmission (metal rope). In any case, even along single track lines, as well as along double track lines, operated under the "Telephone Block" regime, there are no track circuits between one station and another. The freedom from trains on the routes is based exclusively on the phonograms exchanged between station managers. These obsolete systems are being replaced by more modern systems, such as the CTC with the axle counting block for what concerns the single track lines or with the automatic block with coded currents for what concerns the double track lines operated up to now with the block. telephone or with the manual electric block (this also does not include track circuits between one station and another). The FS plans to activate the European system called ETCS Level 2 for the entire network in the long term.

Good question! I'll check with members on the capacity of the Tyer Machines (No6) that we have. In practice though, I think it would be very unusual to have a large number of trains travelling one way with none returning - maybe a town emptying out for holidays (e.g. a wakes week) or a big day at the races. In these circumstances though, I think I have read that the tendency was to create a "very long train rather than have many short ones. Remember if (say) 20 tokens get to one end of the line that would mean that 20 engines, each with their rolling stock and crew, would all be at the end of the line. More plausible perhaps would be where single line working followed a circular route. This could give rise to many more trains in one direction than the opposite. I don't know of any but will see what folks might know and post here, Thanks for the enquiry - always interesting to look at edge cases!

Thanks for letting us know about the film "the Railway Man". It is on Amazon Prime (free for subscribers) and for a small fee on Google Play Movies, You Tube and Apple TV. The film has good reviews and a summary and background on Wikipedia.

My mistake, it's called The Railroad Man (1999), although The Railway Man (2013) is also a good film.

Oh - thanks for letting us know. It seems to be called Poppoya and can be seen on You Tube at kzfaq.info/get/bejne/pa1irdyaq93Un40.html and there is a summary on Wikipedia. Sounds great and a must watch! Thanks again.

Yes - the signalmen are trustworthy and the system relies on trusted relationships. Interlocking systems are predicated on the idea that employees may be hostile, forgetful or incompetent. It is remarkable how simple life would be if people could just trust each other and that trust would always be returned. But if there is any risk, what can the system designer do but design out the risk.

Yes, you make a good point about simplicity. In the system you describe there is trust between the signallers, the drivers and the passengers. A trusted network. The Tyer machine and indeed all interlocking systems arise from a lack of trust somewhere. Not necessarily a lack of trust between the people doing the work, but more usually the people managing the service. Can they trust everyone not to make a mistake, to be forgetful, to be impulsive, to be destructive. If there is any risk, the system designer has no choice, how much risk will the people building the system tolerate? With unlimited funds, we can find unlimited risk. At some point there is compromise and a certain level risk is accepted. Thank you for your thoughts - most instructive on how trust can make life simple.

And people will often take shortcuts and cut corners. It's human nature.

@@sigbox to be fair trust and capacity are 2 different things lets take the fictitious bob the signalman bob would never have a bad intent to anyone even if you really grind him hell save his temper for when your at the pub and whilst on the job takes it verry serious at all times bob can be trusted to always do the right thing but bob is only human and one day bob despite all his trying will inevitably make a mistake even if only a small one anyone could make interlocking is desighned more to cure the mistakes we make rather than not being able to trust each other

Many thanks and indeed, Tyer went through many version of his designs learning from working experience. As with any logic system, old or modern, anticipating all the ways it which it can actually be used and all the modes in which can fail can easily be a never ending task.

Its a judgement call - the clips remove repeats, errors and stumbles not just pauses - some like them out, others don't mind. Takes a lot of editing time and skill to smooth them out and stress we are not a pro media company! Balance at the moment is to deliver the details correctly and as best we have them, but yes there is always room for improvement. Message received - can do better!

Alan = good point (depending on your country of origin) and thanks for the comment - do tell more please.

Note: (RETB) - stands for "Radio Electronic Token Block" - and as Jimmy says, it is derived from single line physical token systems, one of which is demonstrated in the video here. A full explanation from first principals of why the system is indeed fail safe and how the equipment implements the system model would always be good to have.

Yes - Fair play - but we only got so many letters to get across the message in the video title - so really, "how it works" could be said to include the signaller as part of the system.

Many thanks - and in Malay too! A first for us from across the world - so greetings from UK to you.. Translation of uno tapi efisyen - "old fashioned but efficient". How true. - I hope we got the translation right.