Inglenook Sidings Shunting Puzzle

CLASSIC SHUNTING PUZZLES
INGLENOOK SIDINGS

Possibly the most salient feature of Inglenook Sidings - the classic British shunting puzzle par excellence - is its sheer simplicity in terms of track layout: a single line of track ending in three stub sidings.

There may in fact be some modellers who never really look into this shunting puzzle because it may, at first sight, hardly seem to offer much operational challenge.

But as is so often the case, first impressions can be misleading, and it is precisely the simplicity of the "Inglenook formula" which makes it work so well and makes operating it so highly addictive.

Ultimately, it is one of those rare examples where a clever and well balanced combination of a reduced setting and input actually provides an unexpectedly rich end result, and Inglenook Sidings is a picture book perfect example of "reduce to the max".

The stroke of model railway genius embedded in the Inglenook Sidings formula is not only tied to the track layout, but most importantly to the way those sidings are operated. Only when these two elements are combined is a shunting layout transformed into an Inglenook Sidings shunting puzzle.

First of all, in order for a shunting layout to be an Inglenook Sidings puzzle, the length of the three sidings as well the length of the single track leading up to the sidings (i.e. the headshunt) need to conform to a simple set of rules:

- the longest siding holds 5 wagons;
- the two shorter sidings hold 3 wagons each;
- the headshunt allows for the engine plus 3 wagons.

When operating, a total of 8 wagons plus one engine will be used.

The operational rules of the Inglenook Sidings stipulate that a departing train needs to be formed that consists of 5 out of the 8 wagons sitting in the sidings.

The 5 wagons are selected at random, and the train must be made up of the 5 wagons in the order in which they are selected.

The challenge of fulfilling this shunting order is linked to the fact that some advance thinking is required - due to the fact that there is limited space available to juggle around the rolling stock, as determined by the lengths of the individual sidings and the headshunt.

What looks like a simple task can thus provoke quite a bit of headscratching.

The Inglenook Sidings shunting puzzle is the brainchild of Alan Wright (1928 - 2005). He built his first small railway, the Wright Lines, in the early 1950s, and it was on this small layout (consisiting of a "dented" oval and two sidings) that he first had the idea of using a five wagon train on the main line and three wagons in the sidings (the layout was developed over a couple of years, was described and illustrated in the Railway Modeller in 1958, and made a couple of appearances at exhibitions in the North of England).

The way Inglenook Sidings came into being is quite amusing and took place as follows:

Alan Wright (Chris MacKenzie, Virtual Narrow Gauge Exhibition, used with kind permission)

"In December 1979, with the Manchester show approaching, my colleagues at work asked what I would be showing that year and when I said "nothing" I was taken to task and the next day one produced a blockboard off cut 4'0" by 1'0" and challenged me to build a railway on it and show it.

Having some odd pieces of track and a couple of points Inglenook was born and the 5/3/3 formula was adopted. It was a roaring success at the show, I had the small controller on a six feet long lead and stood among the crowd listening to what they had to say and then carried out the movements they wished would happen...

The aura of magic such operation produced made the crowd wonder if it was worked by someone watching on television or was it a computer?" (Alan Wright, personal communication, 2001)

Wright was a railway man through and through and a locomotive engineer in his professional life. He had started out as an apprentice to Hawthorn Leslie on Tyneside in the mid 1940s and then went on to work for Robert Stephenson & Co at Darlington before joining the Vulcan Foundry in Newton-le-Willows in 1964. There, at his drawing board, he was involved in the designs of the BR Class 20s, 37s, 40s, 50s and the mighty Deltics - yet he remained very proud of the Hawthorn and Stephenson 0-4-0ST and 0-6-0ST steam shunters still at work in and around the UK at the time which he had helped to build.

Alan Wright won an award with his shunting puzzle layout in 1979 and later went on to build several layout variations on the Inglenook Sidings scheme.

The inspiration for the basic scheme came from an actual location, Kilham Sidings, on the Alnwick-Cornhill branch (Coldstream branch) of the North Eastern Railway NER. In its original form, the 5/3/3 formula was therefore worked on the main line and two sidings (as per the Wright Lines layout).

On the minimum space Inglenook Sidings layout this then turned into a stub line ending in three sidings. An illustrated article on the second Inglenook Sidings layout (basically a mirrored trackplan with the headshunt going off to the right, whereas the headshunt on the 'original' 1979 layout went off to the left), authored by Wright himself, appeared in the December 1992 Railway Modeller ("Inglenook revisited", unfortunately out of print).

In that article, Wright offered additional insight on his little shunting puzzle, including the origin of its name: "The layout of 1979 (...) was named from the fact that it occupied the space beside the chimney breast, the inglenook." On the original Inglenook Sidings, Alan Wright employed what he called the "Tiddlywink Computer" for this task, i.e. distinct tokens for each wagon drawn from a mug.

Incidentally, the 1992 Inglenook returned to the concept of having two sidings and a mainline, introducing an additional operational complication by having one of the 8 items of rolling stock be a brake van which "can never be moved off the main line".

A couple of pictures of the 1979 layout appeared in C.J. Freezer's Model Railway Manual (first published in 1994, several reprints since) and in the December 1984 issue of Scale Model Trains. Alan Wright also recounted the Inglenook story "so far" in the May/June 1999 issue (#22) of Model Trains International.

Alan Wright's Inglenook Sidings is still considered to be one possible approach to "perfect railway modelling", and quite rightly so. In this ad, a picture from the second version (left-branching) layout takes center stage.

Apparently, the 1979 Inglenook Sidings layout still exists today; when Alan Wright passed away in January 2005 his widow entrusted the original layout to one of her husband's longtime fellow railway modellers.

In essence, the characteristics of this shunting puzzle which make it so effective are:

Simple track layout - it's easy and quick (and cheap) to build or set up

Straightforward rules - they're easy to understand, memorize, and apply

Ready to play in seconds - no extra equipment needed, any kind of token will do

Entertaining - the puzzle is challenging but never frustrating

Non repetitive - 6,720 different shunting orders possible

Small size - makes an ideal second layout

Easy to store - that's where it got its name from

There is a certain amount of befuddlement when it comes to the origins of the Inglenook Sidings formula - due entirely to looking only at the track layout consisting of three sidings (which is, of course, anything but original). Accordingly, even otherwise reliable sources - such as Cyril J. Freezer in his Model Railway Manual (first published in 1994, several reprints since) - link Inglenook Sidings to A.R. Walkley's 1926 "suitcase layout".

Walkley, a member of the Wimbledon Model Railway Club (the second oldest in Britain), published an article on his "Railway in a suitcase" in the June 1926 issue of Model Railway News (reprinted in Model Trains International #83 in 2009). This freight-only folding-layout was a trailblazer effort that pioneered HO scale two-rail operation with locomotives using permanent magnet motors, allowing them to be reversed simply by changing the track polarity.

The lasting influence of Walkley's layout can still be seen on British outline OO gauge models today:

"The layout also featured a system of automatic coupling (really an essential feature for a shunting layout) which later on was marketed by Tri-ang, became known as the "tension lock coupler" and is still used as standard coupler on many UK ready to run models today." (Personal communication, Morgan Lee, longtime librarian of Wimbledon MRC)

Walkley's shunting layout was thus a good many things - but it wasn't the original Inglenook Sidings.

Looking at the 1926 trackplan and photos published in the Model Railway News it is easy to see where the confusion stems from: the track configuration on the right hand side of the layout is the same as the one used with the Inglenook Sidings formula. The difference not evident from the trackplan, however, is that Walkley didn't operate his layout in Inglenook Sidings fashion.

The similarity of the track layouts is all that the "suitcase layout" and Inglenook Sidings have in common; Alan Wright even pointed out to me in a personal communication in 2001 that he had never heard of Walkley or his work when he built the Wright Lines in the early 1950s.