Split-flap Train Display Uses Punch Cards; Serviced with Station Ingenuity

short but highly detailed documentary by [Krzysztof Tyszecki] explores the split-flap display system in place at the Łódź Kaliska train station in Poland as well as the efforts needed by the staff to keep it running and useful to this day. Split-flap displays might be old technology, but many are still in use throughout the world. But even by those standards, the unit at Łódź Kaliska is a relic you wouldn’t expect to see outside a museum. “I doubt you’ll find an original anywhere else,” says a staff member. It requires constant upkeep to remain operational, and meeting the changing demands of a modern station within the limitations of the original system takes some cleverness. “In general the failure rate of the device is terrible,” he adds.

Operator console for Czech PragotronThe system runs on punch cards. You can’t buy them anymore, so a local printer makes them – several hundred are needed every time there is a schedule change. The punching pliers (which also can no longer be purchased) get so worn out they replace the pins with custom-made ones from a local locksmith. The moving parts of the card reader have split-pins which need to be replaced every week or two – the stress of repeated movement simply wears them away. There’s nothing to do but replace them regularly. The assembly needs regular cleaning since dust accumulates on the cards and gets into the whole assembly. The list goes on… and so does the station.

There is no computation in the modern sense – it’s an electromechanical signing system managed and updated by human operators. It has more in common with a crossbar switch based telephone exchange than anything else. The punch cards are just a means of quickly, accurately, and repeatedly setting the displays to known states.

The short documentary goes into a lot of detail about every part of the system. The cards themselves are described in detail (1:07), as is the operator’s routine (2:27). We even see the back end controller (9:41), as well as see a split-flap module taken apart and tested (14:33) with an old tester the staffer isn’t sure will even work – but as with everything else we see, of course it does.

Split-flap displays are fascinating pieces of technology. We have even seen people build their own split-flap displays from scratch!

(Editor’s Note: [Krzysztof Tyszecki] wrote in to say that he’s writing a book about old train-staion split-flap displays, and would be grateful for any info or stories that anyone wanted to share with him. His e-mail address is firstname.lastname@gmail.com.)

Thanks to [piachoo] for bringing this to our attention!

36 thoughts on “Split-flap Train Display Uses Punch Cards; Serviced with Station Ingenuity

    1. You have to realize that the labour costs are cheap there. An average railway worker in Poland (or Slovakia where these are also still common) makes perhaps $500-600/month.

      So unless the station is going to be modernized in a near future, they will keep paying the maintenance guy to clean and fix these Pragotrons for a long time. A new system for a larger station is fairly expensive, especially because they are typically tied into the traffic control system and fully automated (they can’t just replace the displays!).

        1. And then what happens to the employees that your new technology make redundant?
          What happens to the local printer who no longer get the order to print new cards?
          What happens to the locksmith who provides the pins?

          1. What happens with the 5000 people living in a small town nearby that got its train line closed, because there is not enough budget to maintain it, because all the money go into supporting ancient hardware and employees who sit all day and do nothing but punch cards? Before you start shouting “think of the children”, better get your priorities straight first. Transportation is the blood of economy — if you can’t get to the nearest city efficiently and cheaply, that means you can’t get a job there, and you can’t go shopping for better/cheaper stuff, and you can’t send your children to school.

        2. If you buy a $300 tv, you’d better hope the store has a very good refund policy even for home use. For effectively always on use in a signing application 40″ is going to bee too small and a $300 tv will burn out way too fast.

      1. You don’t even have to replace it whole. Heck, get a Pi Zero and rig it in place of that card reader. Have a 10-line Python app that reads the schedule from an Excel file, and automatically posts the trains. Add a 20-line web app for posting last-minute changes. Total cost: $5 + two evenings of work of a technical school student.

          1. The thing is, they are having all this fun (and employing their family members at useless jobs) for my tax money. Meanwhile they are “reducing” the number of trains going, or even closing whole lines, due to “not enough budget”, leaving whole villages and cities effectively cut off from sources of employment. I don’t really care what they *want* to do. They are a state-subsided company that has obligations towards the general public.

    2. Unless you know all the details it’s impossible to make this assumption. This is not the only station in this city and putting money elsewhere may generate more revenue, especially when you consider the fact that there a few big rail investments going on in that station’s close neighbourhood.

      Apart from that, you still need people on site since they have to watch the devices – when summed up, it may turn out that instead of replacing displays now, it’s better to wait a few months and finish the other, more important works.

      As for the upgrate to uC/Raspberry/PC in place of the reader – They are able to do this and it was done on many stations as a standard upgrade. But it wasn’t conducted in Łódź because the rail company wanted to do the full upgrade (to some new system) there. As you may have already guessed, this was delayed a few times and that made this video possible.

      Source: I made this vid

        1. I’m glad you all enjoy it :)

          The video is a part of my larger project – I want to publish a book on history of these systems. Right now I have support from the Polish State Railways (they allow me to make stuff like this video and give hints) and I also have appointment scheduled in a factory that used to make split-flaps. There’s some small museum in Germany that has some very old displays from GDR times and I want to visit it too.

          It’s really damn hard to find good information on them. Even Solari doesn’t publish a lot about the first ever split-flap installation (that was in Liege).

          If you got some info, drop me a mail (my name dot my surname at gmail) or send me a message on YouTube, I already know that there’s a Krone board in Utrecht museum thanks to this thread. And I’m replying to you, since you can tell the manufacturers apart, so maybe you know some more interesting details :)

  1. We’ve had one at the local train station of the last in The Netherlands. Sadly they’ve retired the display a few years ago, while renovating the train station. (Being expensive to maintain was one of the issues). It since has been replaced by a really bight and ugly LCD display matrix. And it’s mainly used for advertising and not for departure times…

    The display can be found at the train museum in Utrecht, The Netherlands. They’ve done they’re job of hiding it, its not operational either. I would go to the museum just to hear the flipping/clicking noise.

    This is a video of the split flap matrix. The video has the clicking sound. The video it self is bad in quality, its probable recorded with a phone of that time. (We are blessed with the technology of today)

    1. The Blue Sign was one of the best. Made by Krone, it was one of the landmarks at Utrecht Centraal and the default meeting spot when you wanted to make sure the person you were supposed to meet with, would know where to be.
      As you said, now it’s tucked away in a dark corner at the Railway Museum.

      The main problem with the alternative LCD version is the inverse colour scheme. For those not from the Netherlands: the current colour scheme is dark blue on a white background. Not only is is it awfully bright, it’s also harder to see from a distance what’s on the sign.
      The subways in Osaka use bright colours on a black background for their announcement screens. Much easier on the eyes and clearly readable, whereever you are on the platform.

      If only NS would see it that way…

  2. Actually these Czech-made Pragotron displays along with the typical looking split-flap clock are still fairly common on the railways in both Czech and Slovak republic – they were the standard fare in all larger stations. If you google for Pragotron, you will find a lot of photos of these. They were also used at airports and some large bus terminals. They are being slowly replaced with LED based displays as the lines are reconstructed and modernized.

    And if you want to see a really huge split-flap display (not a Pragotron, though!), there is one in Paris at the Gare du Nord:

  3. Would seem like a simple proposition and less long term hassle to leave the bulk of the hardware untouched, replace the actual input device and hook the whole thing up to a computer.

    replace a bulky manual and tons of punch cards with a set of dropdown menus and an update button :P

      1. Well I suppose the computer the lady making the punch cards was using is probably connected to the internet so by proxy of likely being hooked into the same system then yes?

  4. Wear rate seems to be too high for punch card systen too. I’ve seen many jacquard looms run 24hrs/day 365 days continuous without faliure of selector pins. And cards read in looms is way too frequent than this.

  5. In the NC/CNC world, there’s a device called a “Tape Twin,” which is essentially a paper tape emulator for when the tape mechanism is too slow/high-maintenance but the tool and its controller are otherwise fine.

  6. I wonder how expensive it would be to create “the punch card to rule them all”?

    What I have in mind is a thin PCB or a flex assembly that you slide into the slot once and for all in order to simulate a punch card. This special output device, controlled from an off-the-shelf PC as the one in the background, would eliminate the need for paper punch cards, reduce maintenance of the reader itself and replace the manual encoding process by using a GUI on a PC. It would not require any modification of the Pragotron system at all. The only costs are purchasing the device and the training to change the procedure of entering information.

    The socially concerned may lobby to pay the printer a retainer for not printing punch cards any longer.

    The video shows a punch card at 21:31. It has 15 (or 14?) x 8 encoding positions, with 4 fixed holes for alignment. The material is ordinary cardboard, maybe 200 g/m^2, of size at most A6 (= 148×105 mm). Since the reader has a flat cover, I suspect that the upper side is simply a single conducting plate at ground potential, and there are spring-actuated rounded pins sliding from the bottom through the holes into contacting the plate. That would require a single-sided flex with 116 encoding contacts and a single elevated ground contact on the other side. Since the human-readable part of the card sticks out during operation the reader does not close the slot. So there is enough room to get 117 wires out. As far as electro-mechanics is concerned that is about it. (Later it may be useful to actuate button as well, or maybe not.)

    Electrically, the only voltages mentioned in the video are 40 V for actuating the flap box, and 100 V as the main power (to run the motors?). Since there are diodes for demuxing, I am assuming the system runs on DC. The only amplifiers I see are chunky relays at the flap boxes, but at 10:12 the video also shows a little PCB. Since there will be many displays around the station to show the same information, I think it is unlikely that the reader contacts carry the power for the flap boxes without amplification, but it is possible. The Czech engineers probably invented a form of multiplexing and addressing to reduce the wiring. For this, however, more information is needed what the reader contacts are driving. In a fortunate case, 17 x ULN2001 might be sufficient (7x Darlington arrays 50V 500mA max incl. diodes for inductive loads, < 0.5 EUR/IC) to switch the 116 contacts. The biggest concern beyond that is electric safety.

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