Sunday 14 August 2016

Guest Post - Shunting

Hi everyone, it's been a really busy week for me being on call plus long days then, with my insomnia making me crash in the evenings and having to yet again write the consultant on call rotas yesterday, I have had a week with absolutely no puzzling in it at all! Not a thing...nada! Sob!!! Even Mrs S noticed that I wasn't playing as usual. I am therefore, so grateful to the Puzzlemad roving reporter, Mike Desilets, for producing a wonderful article for me. He always seems to know just when to drop something into my inbox. I'll hand you over to him just now. I am sure I will interject the odd comment now and then.

Historical Shunting designs
(This is a screenshot from Rob Stegmann's extensive page on the subject)
Aloha Kākou readers. Just popping back into the blogosphere for bit. I was originally planning to present Part 2 of the MrPuzzle post - the workshop tour - as my next Puzzlemad hijacking (Ed - I'm waiting with bated breath!). I will do that, eventually, but this past month I was inspired by some other events and research which I’d like to get off my chest. This post is not a straight-up puzzle review, but more along the lines of puzzle advocacy. Specifically, I am advocating for some enterprising designer/builder to fill a notable, and unacceptable, void in the puzzle world - an almost complete absence of mechanical shunting puzzles. It’s an admittedly obscure subset of (I assume) the sequential movement class, but I’ve become utterly fascinated with them over the last few months. If my enthusiasm is even partly transmissible to the community through Puzzlemad, then maybe resurrection of this time-honored puzzle type is possible. Further down I’ll throw out a particularly intriguing design I came across, developed by a notable model railroader.

So how did I come to the conclusion there are not enough (or really any) shunting puzzles out there in the wild? Well, first you have to know how I even became aware of these fascinating puzzles, or rather, reminded of them. Let’s retrace my steps, shall we? Don’t worry, it’s a short trip, and I’ll even throw in some pictures to keep you occupied. Cue music.....

It all began a few months back when I was out on a run in the neighborhoods near my house. I Have recently reached the age where I can refer to myself as being at a “certain age”  (Ed - I got there quite some time ago), I’ve come to the realization that knee joints are not designed to take repetitive impact for long periods and, quite likely, did not even evolve to be useful beyond that “certain age”. That’s a problem for someone who is accustomed to a steady dose of exercise-induced endorphins (Ed - I always thought exercise was bad for you but when Mrs S threatened to chuck me out if I got fat, I took up exercise and lurve those endorphins!). A great solution for me has been running hills. There is hardly any impact running up a hill, and boy will it get your heart rate up fast. On one particular death-run, I crested the summit and paused to enjoy some well-deserved wheezing. While collecting myself for the next go, I casually inspected the ever-present pile of trash by a particular neighbor’s house. I am always fascinated by what people put out on the curb (a professional bent) so I can’t help but look over the pile. Junk, as usual. But one thing catches my eye. This:

A prize from the roadside. Some water damage, but still collectible. Make an offer.
It was dark and I couldn’t tell exactly what it was, but my puzzle-sense was tingling. I separated it from the rest of the junk and realized it was a child’s toy of some sort. The kind that have various do-hickys on the sides for kids, really young kids, to play with. The box itself serves as a toybox. It’s fairly unremarkable except for the one side that had the slidey puzzle you see in the picture. That really caught my attention. Everything else on the box appears to have been designed down to little kid level, or lower, but this side presented a not-exactly-trivial puzzle. Assuming, of course, you really mix it up (which I immediately did). I was impressed that anyone would think to subject little minds to such a challenge. I don’t know how many children meet the challenge, or how many even enjoy the experience. I bet it’s a limited number. If we knew who they were, we’d probably have a good idea who the next generation of Nobel laureates and super-villains will be. Anyhow, it was puzzle-related, so of course I dragged it home.

The box was duly deposited in my garage for future inspection. Following a quick meal, I went out to play with my prize. Seeing that rest of the box was worthless, I detached the puzzle panel. Now, presented with any puzzle, especially one I feel confident I can master, I do the natural thing: mix it up, take a few moments to forget what I just did, then proceed to solve. This one turns out to be pretty easy for an adult, no surprise, but it was not unenjoyable. Twenty pegs of four colors and a bunch of tracks to follow gives one plenty of movement options. Solving just entails moving things out of the way as you shift like colors next to one another on the lines. Add a time element to this process, however, and then you have a challenge. It’s easy to solve, but are you solving it the most efficient way possible? You can gauge this to some degree by timing yourself, using the same starting position of course.

The puzzle isolated from the rubbish.
The hammer is NOT for solving it
The back face
similar to the front
Rudenko's disk
A pretty neat little find. It kept me occupied for a little while, but there was something nagging at me. I’ve done similar types of puzzles before, haven’t I? Or seen something like this somewhere? I couldn’t put my finger on it exactly. In a certain way, it reminded me of Rudenko’s Disk (see Gabriel’s write-up), though obviously much simpler. But sequential movement along a series of linear tracks, nonetheless. I thought maybe it looked like a Constantin puzzle I had seen (or dreamed). Checking the Puzzlemaster compendium, I found a few sequential movement puzzles, but nothing with significant track arrangements. A week later I saw another, very much simpler version of the child’s sliding puzzle. It’s a pretty common theme, it seems. If you survey a good toy store, you’ll find that puzzles are highly integrated into toys for very young children, infants even, but that they really drop off around age 6 or so. Still some games, and the ever-present 3x3x3 cubes, but the trend is clearly toward “toys” in the traditional sense. This is a real shame. I expect the puzzle-type toys are marketed to moms and dads as a way to (supposedly) stimulate brain development. At a certain age, marketing shifts to the kids themselves, and then dolls and toy cars take over. Mechanical puzzles are thereafter relegated to an “oddball” category, only to be rediscovered later in adulthood, if at all (Ed - that's pretty close to my story).

Sequential movement aimed at very young kids
Anyhow, after a short period, I had my Ah-ha! moment. I raced to the bookshelf and yanked down my prized copy of Van Delft and Botermans’ Creative Puzzles of the World (if you don’t have a copy, stop reading this blog and go order one immediately). Sure enough, the source of my irritation was on page 177. That was where I had subconsciously remembered this type of movement. Train sidings and switching problems, otherwise known as shunting puzzles. Van Delft and Botermans run through four or five types based on different track arrangements, but let me sum up the central issue for the majority of shunting puzzles: two trains need to pass each other on a track, and there is a siding that will only accept a small number of cars. So how do the locomotives and their cars pass one another and get on their way? Through countless back and forth movement of the cars on and off the siding, that’s how. In real life, railroads solve this problem by simply building nice long sidings and two trains really shouldn’t meet head-on at a siding. That would be very poor scheduling indeed! So in a very real sense, shunting puzzles are largely made-up problems. When not totally made up, then they probably relate to issues only relevant to the very earliest years of railroading.

Main line and siding, the fundamental shunting layout
At this point you may be wondering how a child’s slidey puzzle relates to railroad switching. Well, the relationship in my mind involved the two-dimensional linear track and the principal of moving things sequentially out of the way, into the way, out of the way, and so on until a desired arrangement is reached. That’s about it. Two-dimensional sequential movement. The real distinguishing feature of the shunting puzzle, however, and what relates it specifically to trains, is the fact that the moving pieces come in two classes: the locomotive and the car. A locomotive can move independently, but a car must always be moved (be paired) with the locomotive. This complicates matters greatly and lays the groundwork for real puzzling. Go back to my puzzle above and imaging that one of each color is marked with an X as the locomotive, and then assume “train” movement rules (recall that locomotives can push or pull, so that helps). The puzzle takes on a whole new dimension (Ed - it certainly does! This is the point at which I suddenly realised this was a great post). All we did was institute the pairing rule; a rule that was only conceived (to my knowledge) thanks to railroading. What are the chances that such a simple but somewhat contrived rule would have been independently invented and applied to mechanical puzzles? Not high, I’m guessing.  

So I finally scratched the itch and now the research began in earnest. Van Delft and Botermans illustrated a very simple shunting puzzle with a few cars and a single siding. Unfortunately, it is not so much a puzzle as a tool for exploring the switching concept. My next step was to check Robs Puzzle Page, by far the most comprehensive web-posted puzzle collection, meticulously organized and updated by fellow New Englander Rob Stegmann. As expected, Rob had shunting puzzles, and a lot of interesting historical patent info on them as well. The earliest known shunting puzzle design dates to 1885. Not unexpectedly, train shunting puzzles enjoyed a flurry of popularity during the golden age of rail. As with patents generally, I suspect most of these shunting puzzles were never commercially produced. But the age of Victorian parlor puzzling was ramping up and many designers saw railroading as a source of inspiration. Rob’s page shows 27 different railroad-based puzzle patents, many of them using a triangular track arrangement. Following this are eight actual shunting puzzles that reached market. But don’t get your hopes up. Most of these are long out of production. The most recent seems to be a Bits and Pieces model called Train in Line. It is composed of a short serpentine track, split in the middle, with five cars and an engine. It looks nice but, of course, is no longer produced:

Train in Line from Bits and Pieces.
Image from Rob Stegman’s shunting puzzles section. Hopefully he doesn’t mind me showing it here.
After checking in with Rob’s site, I wandered over to to check the holdings of the Hordern-Dalgety Collection. This only produced one shunting puzzle, but a very intriguing one. Rob shows this puzzle too, and notes that it can be found in Slocum and Botermans’ Puzzles Old & New. He also has a link to the original patent from 1890. Very cool, but you will probably have to wait a while to find one on the market!

Engineer’s and Switchman’s puzzle in the Hordern-Dalgety Collection. Patented in 1890

Searching the trusty interweb more generally, I couldn’t find any shunting puzzles available for purchase. Readership, take that as a challenge and please prove me wrong. Like my editor/publisher (and friend) Kevin, I do this in my spare time and am admittedly pretty spent by the time I get around to it. My searches are cursory at best.

However, during my web search, I was rewarded with an absolutely fantastic website on shunting puzzles put up by our distant cousins in the model railroading world. The site is here and most of what I am about to say I gleaned from it. It’s a great page and I encourage you to explore it in depth. It turns out that model railroaders are huge (to put it mildly) fans of shunting puzzles, partly for the reason puzzlers are (the thrill and fascination of the solve), but also as a way to increase enjoyment of their hobby. Shunting gives you something to do with a model track, as opposed to, say, watching your train go around in circle. Designing a shunting layout with complicated switching arrangements, and then implementing and running it, is a real challenge. Even as a non-railroader I can see the attraction. It looks fun. (Ed - Aaaargh nooooo! I daren't get into that as a hobby.....even a Whack! Ouch! wouldn't suffice as my punishment from she who frightens the bejeeeezus out of me!)

Although switching and sidings are standard fair for model railroaders, model shunting in the modern age (second half the twentieth century) traces back to two archetypes discussed extensively at the webpage above. These are the Timesaver, invented by John Allen in the early 1970s, and Inglenook Sidings, first developed by Alan Wright in the 1950s. John Allen’s Timesaver involves switching five cars to their preset destinations on the layout and doing so in the quickest time possible, or using the fewest moves possible. Traditionally, the puzzle was played with cars in the same starting positions so players could compare their skills.

John Allen’s Timesaver shunting layout, five cars and an engine
(image from the linked website)
As much as I like the Timesaver, I am drawn much more to Wright’s Inglenook Sidings. I think puzzlers will appreciate right away the beauty of the design. It is simple, but contains within it a bewildering variety of possible puzzles and solutions. Inglenook Siding has a main track, a siding, and siding off that siding. On the track are eight cars and an engine. To play the puzzle, five of the cars are selected through some random method. These cars must then be arranged on the main track in the order in which they were selected. With eight cars, the number of possible positioning combinations is (I am told on the website) 40,320. So you are unlikely to repeat a “puzzle” very often, let alone remember the solution (Ed - I don't remember what I did yesterday!). This puzzle has all the qualities of a great design, the only problem being that you need to construct a model train layout to play it (or you can try one of the many electronic versions). Personally I don’t have the time or inclination to do the former, and I find electronic puzzling largely unsatisfying. I need a mechanical puzzle to manipulate and enjoy. (Ed - me too)

Alan Wright’s Inglenook Sidings, a modern classic
(image from the linked website)
Unfortunately, I don’t have the skills to convert the Inglenook Sidings puzzle into a proper-sized mechanical puzzle. But I know many readers of this blog do. It would be doing the community a great service to get a shunting puzzle or two into production and on the market. This could be a great and stimulating adventure for the right designer. There are many expired patent designs that can now be reproduced, or used for ideas, right off the shelf, and the possibilities for new shunting designs are almost limitless. We are only talking about sliding pieces after all, and maybe some magnets to hook and unhook cars. Inglenook Sidings, I believe, deserves serious consideration. There are no copyright or patent issues at this point, just give Alan Wright the credit he is due. And know also that shunting puzzles exploit two markets: puzzlers and model railroaders. In terms of saleability, I think a good shunting puzzle would be a money-maker and it might very well have more long-term appeal than many of the newer puzzles. These are classics after all, and they have the capacity to capture the imagination. We have not seen shunting puzzles in any serious way since the turn of the century and I believe they are due for a comeback.

So that’s my pitch and the end of the story. I was brought to the exciting world of shunting puzzles by way of a child’s puzzle found on the side of the road. A strange route, but none the worse for it. Hopefully shunting puzzles are as fun to play as I claim they are. And hopefully we will all get to experience them in the not-to-distant future. Back to you Kevin.....

Thank you so much Mike! That was a great trip into a totally new area for me. I agree that it is a ripe area for a good woodworker to produce something beautiful. Hopefully one of them will read this and will jump on the challenge.


  1. Replies
    1. That's why I love it when Mike writes for me!

  2. Great stuff! I would not be surprised if "Inglenook Sidings" was already available as in iPhone App. As an app is not a real mechanical puzzle, but often cheaper (free!?) and allowing the same manipulations.

    Have you seen the shunting puzzle iPhone App "Subway Shuffle"? A modern take on the idea. There are certainly many "digital shunting puzzles" (implemented on a screen, not mechanically) which could make for a whole part 2 of this article!

    1. I wonder whether it is? I'll do a search when I get a moment. I have definitely played a game/puzzle on the iPhone called Trainyard which took the world by storm a few years ago and it was a great idea. Unfortunately apps and computer games don't quite do it for me. I only play when there's nothing else.

  3. Hi George, yes, you are quite right, digital shunting is available. Just played an app on my phone called simply "shunting" by jeppe teensma (2014). Inglenook sidings. Pretty fun once you get the manipulation down. Great sound effects.

    Hadn't thought of a part 2, and talking digital would be new, but now you've got me thinking....

  4. UPDATE: For those that are interested, there are a couple of classic shunting puzzles for sale at the Puzzle Museum, including the Engineer’s and Switchman’s puzzle shown above.

  5. In the book Sliding Piece Puzzles by Edward Hordern there is a chapter on Shunting with 13 puzzles. Great article!

  6. Thanks Theo, that's a great reference. I definitely need to add this to my library. I did manage to find it online here, if anyone wants to check it out, pp167-177:

  7. Just noticed this article - very well written! I love the Inglenook puzzle myself and, as an armchair railway modeller, have consoled my obsession with the best mobile sim I have yet found on IOS: Tiny Trackz. It's not free, but it's very well designed & playable and fully animated (note I am only a happy customer, with no link to company, etc.):

    It also has a 'kids' mode, with only 5 wagons instead of 8, so my 5 year old son now happily solves puzzles in this mode when the mood takes him.

    1. Thanks for the link Alan, I'm sure quite a few of us will find that useful. Glad that you enjoyed the article from Mike.