Layout design for realistic operation
by Harry and the late Ivor C. Marshall.
© Harry Marshall 2006
The right of Harry Marshall to be identified as the Author of the Work has been asserted
Pencil, Paper and Rubber
Most of the previous part of this article dealt with the variety of problems and challenges placed in the way of the railway operator, who after all is only trying to move the customer’s goods, and the customers themselves, efficiently and economically. A few of the strategies employed were also described, and I should stress at this point that that material was not intended to be a complete review of railway freight or passenger handling, merely a flavour of the subject to trigger your own research.
Now the pencil, paper and rubber can come out. From this point on, a fairly sharp division occurs between those who are adapting a piece of reality and the ‘might have beens’ group. May I at this point claim total impartiality between both approaches. I have been involved both in an operating model of the Somerset and Dorset, and a fictional branch line layout set on the Dorset coast. This article was prompted in part by my experiences!
Modifications to a Prototype
Considering adapted reality first, if you are “editing down” an existing station layout, it should be possible in light of the previously mentioned considerations to see which sidings can be shortened, shared or removed. Be careful, though, that no reversal of a siding occurs, and that you do not accidentally remove a run-round loop, however well-hidden it might be. Of course, the trap points (not catch points, they’re different) must stay in place, but it is usual to find a fair bit of redundant trackwork in a station design, particularly from the years between 1920 and the Beeching era. Certain features that are specific to the location being modelled and form a part of its essential character should now become more prominent, and as an example, may I quote the famous middle siding at Evercreech Junction, S.D.J.R. Without this feature, the whole character of that station design is destroyed. Look at your chosen stations through operator’s eyes, and their individuality becomes more apparent. There never was a perfect way to achieve all the operationally desirable manoeuvres at most British stations- as fast as alterations were made to adapt to a new situation, so the pattern of services would change again!
There are one or two design tricks available to us modellers, though, and some of them are suggested by reference to Evercreech Junction, a part of which is sketched out as figure 1. Consider the area between the platforms, and what might be achieved with a single slip in the down road, rather than the diamond crossing which actually existed. The crossover immediately to the south (right) of the access to the local yard becomes redundant, and you gain its length (about 18 inches in 00) for other uses. This is depicted in figure 2. It is not, however a good idea to go the whole way and put a double slip into this situation. Complex track features such as this tended to be frowned on by the Ministry of Transport in fast running lines. Also, they are not the easiest of items to make if you are new to pointwork construction. Note the two point replaced by a double slip on the centre road siding, this change reduces the overall length still further (by about 9 inches in OO).
Rules of Access to Sidings
Another feature to avoid, if you can, is the use of facing turn-outs for access to siding areas, (and a double slip is such an item). In reality, not only were they not encouraged by the authorities on safety grounds, but they required the use of separate lever operated bolts for locking: more expense, more labour! Not that this directly affects modellers, other than by the increased accident risk of a facing turn-out, which in our combined experience is considerable. Those of us with single-line prototypes inevitably have to accept, however, that every running line turn-out will be a facing one at some time…
The real benefits of the several varieties of slip, interleaved point and three-way turnout occur mainly in sidings, and particularly in avoiding shunting moves across several roads through a succession of S-bends or reverse curves. This is another recipe for repeated derailments, for a number of reasons, having to do with buffer locking, differences of weight between vehicles and so on. Do not forget the scissors crossing formation, either. This tended to be widely used on the London Underground as a space saver, being particularly suited to unit trains and cramped locations. It is seen on the surface as well, and may be a feature of your chosen location. If it is, keep it if you can. If not, use it carefully, and perhaps try not to make it visually obvious, as it is a “busy” looking piece of point-work which could jar with an otherwise simple and fluid appearance.
To be really successful with a redesign, it is necessary to construct or reconstruct the timetable for the proposed layout, in full, and for all seasons and traffics. Then a means must be found of running through it (a ‘dry run’) on paper to establish that the proposed plan is capable of handling all expected situations realistically, essentially in the manner of the original. This amounts to operating your layout before it even exists, which may seem perverse; however, it does replicate reality especially when any major reworking of a track layout is in hand. (See forthcoming article on operating schedule construction – Ed). For this purpose, vehicle length data is required, and not just over buffers, either. Measure the length of a few wagons, couplings taut, and compare with the sum of individual overall dimensions over buffers, and draw conclusions for your other proposed formations e.g. rake(s) of coaches. If possible, try and allow a little redundant length in platforms (and sidings); use of every inch of platform length all the time is restricted in reality to the main London terminals, with very few exceptions. There, space and traffic density at rush hours absolutely dictate the use of the full length of every platform. Elsewhere, trains have almost always been significantly shorter than the platforms they used, for most of railway history.
Fictional Railway Designs
For those adventurous souls who decide to enter the realms of the fictional railway, there is another approach available, which has its origins partly in the toy train set that most of us began with. If the initial seed of enthusiasm for this hobby took root, did we not begin by expanding from the first simple circle of track to the purchase of perhaps one turn-out, and some more rails. And then another, and some more rails; and perhaps more…..
The problem most of us landed in, entirely through blameless ignorance, was that the contorted ovals and all-embracing yards that we ended up with arose because we had no concept from the start of our expansion of the layout of what the ‘final’ form might be.
The Right Start
With the passing of years and greater knowledge, it is possible to begin again from a similar starting point, but this time, develop our design in stages as means allow, with a final form in mind. This implies that we have a pretty clear idea from the start of a layout about what sort of places we intend to represent, the period considered, and the kinds of traffic we wish to show being moved. At this point, switch on the imagination, and invent your locality, period, expected traffics, and perhaps relate to a likely parent Company that would have been associated with your line. (This helps research into favoured operating methods.) Consider what vehicles would be required to move the traffic of all kinds offering, and what operating techniques would be appropriate to dealing with it all. Do you need a run- round? Is there a terminus? Will motive power servicing be appropriate somewhere? And back to the real world, what space do you have for it all? This is what usually produces the ‘geographical’ constraints in a fictional design, and has no lesser impact on adapted reality.
It may be that the layout is a first attempt at a design of your own, or perhaps it is intended to be a ‘pocket money’ development, that is to say, the layout grows as pocket money allows. If so, the following step-by-step approach may be of interest. The assumption as far as space is concerned is that something like a garage, probably shared with the car, is the proposed location, and perhaps one or two terminal stations, feeding a continuous circuit, or working end-to-end are wanted. Earlier, the thought was offered that some idea of a final design is desirable from the outset, and this sequence of developments points the way to achieving that, but having a satisfying and realistically operable layout from the outset.
So that the (possible) target may be appreciated from the beginning, four ‘eventual’ terminal designs are given as figures 3 to 6 below. No loco depots are shown at this stage; they need some explanation, and are covered separately in the Final Part of this article. The whole idea behind this concept is that changes and developments do not involve wholesale rebuilding, only anticipated additions to what already exists.
Note the following drawings are not to any scale, they are intended to show the relative positions only.
We begin with a single line coming from ‘some distant place’, and ending at one platform, such as only a multiple unit or push-pull train would use. Not prototypical? Take a look at both modern and past rural branch lines. Now, our single line may one day be doubled, so we need to have the ‘land acquired’ to allow for this. Since double lines don’t end at single platforms, and anyway, perhaps we want to run something more than just multiple units, then access to a siding is the next logical step. This can be made in any of four directions, facing/trailing or left/right. For the present, let us go with facing, left. Admittedly, the “yard” cannot readily be shunted by the incoming train engine, but at least interest is increased by the need for a local shunting or layover (i.e. previously arrived) engine, so that the latest arrival can be released and stand aside for the next train. In parenthesis, there is an opportunity to put in realistic signalling, a simple five-lever frame being all that is required, at this stage anyway. The story so far appears as figure 7.
The ‘greyed-out’ line and structures indicate still further possibilities. Notice that the connection to the running line is not a single point, which would be sufficient in theory, but a crossover, incorporating the ‘trap’ function. This might seem to be unnecessary in such a simple layout, but is correct practice as mentioned earlier, and is forward thinking towards the next stages, see figures 8 and 9.
It is now possible to see several ways in which our basic station could develop. For example, the suggested engine shed might be moved elsewhere to give an adequate shunting neck for the expanded freight facility. The offset in the shed road can now be seen as the site of the revised access to the shunting neck in consequence of doubling the incoming line. The two turnouts involved (orange crossover) could have been sited at an early stage and ‘locked out of use’, as per reality, if this was in the final plan.
The set of possibilities shown as crossovers coloured brown and blue, in figure 9, is worth some study. It may, for example, be decided that all arrivals will come in to platform 2, but that departures can be from either platform. In this case, only the orange and green crossovers are required, platform 1 being accessible by shunting through the green one. However, if both platforms are to be used for all purposes, we need another crossover either the brown or blue. Which of these possibilities we adopt depends on whether we want direct access to/from the sidings to platform 1, or do we wish to operate the siding area as a separate control position, allowing independent operation into and out of platform 1. Platform 2 would then be the exclusive interchange road for freight movements. A double shunt is required if the blue crossover is employed, to get anything from Platform 1 to or from the yard, whereas the brown crossover allows a departing freight movement with one shunt only. The choice is between ‘play value’ and efficient operation, but a father-and-son layout might well favour the former.
Notice that another subtle change has also occurred. The access to the sidings is now via the orange crossover, not green as before. This arrangement tends to be more common in reality, as the result is that the siding ends, and the unloading facilities are next to the station buildings, themselves usually next to the access road to the station. The other way round is sometimes seen where a large specialised facility is located back up the line a bit, allowing the headshunt to lay next to the station. Quite a useful idea when layout width is restricted.
Observe also the appearance of the loco release crossover in the platforms. This introduces its own set of problems and opportunities. The main problem is the necessity of keeping Platform 1, except the buffers side of the crossover, clear of obstructions when trains are arriving, unless an immediate departure of another train from Platform 1 is intended. There is also the balance of lost platform length against the need for another locomotive, see previous comments, but applied to your model and available space. Against this, you have the chance to show parcels traffic, mails or newspapers handled at the platform by means of a van or vans parked in the end of Platform 1. It is also possible to so locate the crossover so that the little local engines can use it easily, but not some large visitor from afar, who will require the summer Saturday station pilot to release him!
At the start of this build-up sequence, Figures 3 to 6 were mentioned. Each of these is a possible development of the thinking so far described, including one form of ‘mirror image’ for the approach from the right. It may be that you want to ‘mirror image’ for sidings towards you, not away as so far shown. Not a big problem, except that now arrivals are on the side remote from the sidings, and access means a shunt ‘across the lot’ for an incoming train. Of course, the loco release crossover cannot be done with right-handed points, this has to stay as it is. Having said that, I am sure someone somewhere will come up with an example of a place where that last statement is untrue. This is why virtually every part of Britain’s railway network has (or had) its own Appendix to the Rule Book, in which the special arrangements for working a station arranged “back to front” would be set out, along with all the other practical divergences from normal or ideal working. This is where research comes in again, or thinking it out for yourself, to cover the needs of your own particular brainchild. Suffice to say that working a station “cross-handed” like this would be very inconvenient, to say the least, and the reasons for doing it would have to be very strong indeed.
The next (and final!) part of this article is a brief look at the age of the steam Motive Power Depot (MPD), from the operation point of view.