Double Deck Construction

Multi-deck construction: a consideration of the whys and wherefores.

The decision to construct a multi-decked layout is not one to be easily taken. It is tautologous to state that it is simpler to construct a single-decked layout. The question might reasonably be asked, then, as to why put up with the complications? Hopefully this essay will give an insight into the deliberations that encouraged the construction of my own three dimensional jigsaw. These considerations are not restricted to 7mmNG modelling and so my thoughts and experiences may be of interest to others contemplating the construction of a multi deck layout.
Layout plan
The general arrangement of the layout can be seen by clicking on the buttton above.
Theoretical considerations
The AFK was designed from the outset to be focussed upon operation, if necessary at the cost of scenic considerations. The complex scenario envisaged for the railway could not be achieved by one run around the room's perimeter. A long mainline was required and the layout's footprint had to be maximised. A multiple level layout was the only sensible approach to meeting these desiderata. Multi-decked layouts are much more common in the United States than they are in Europe. It will come as no surprise, therefore, to find that the definitive work on the subject is published by Kalmbach, with Tony Koester as the author. [1] The book gives an in depth consideration of the points made here and also provides detailed observations of others that are not. I would recommend reading it for an insight into the construction of a multi-level system if you are contemplating building such a layout. (Ironically the AFK was finished, in outline, before the book’s publication. Had it been available earlier I may not have found myself re-inventing the wheel.) In the UK, however, I doubt that many modellers are aware of the book, primarily because it is only available from specialist importers, which are perhaps not the first port of call for most people designing a new layout. In any case multi-level layouts are usually associated with American modelling, with the background assumption that the builder has a large amount of space to house the layout, and are not therefore applicable to the British scene. This is not necessarily the case, although it has to be admitted that many US multi-deck layouts do occupy a large basement. Magazines such as Model Railroad Planning have, however, shown that an aircraft hangar is not a pre-requisite for such a layout. British modellers have in the past built their own multi-level layouts, but, until the advent of Koester’s book, finding information about the practicalities of their construction was rather like looking for a needle in a haystack.
Having built a multi-decked layout myself, it would be very easy to advocate this as a great leap forward in model railway planning, and to disparage layouts designed on the single level principle. This would be to overlook the space constraints within which many modellers work, and the type of railway scene that they wish to replicate. The AFK is built in a room 22 foot long by 9 foot 3 inches wide, which was the space intended for a garage alongside my house. This is a large space in the British modelling context. From experience, I would suggest that the area approaches the minimum dimensions needed to adopt the multi-level approach for a conventional layout. Multi-decked layouts create at least as many problems as they solve and any-one contemplating building such a layout should be aware of this. In my prevailing circumstances I have no regrets in building one, but I would be amongst the first to acknowledge that it is not a universal cure to the problems of all modellers.
It has always puzzled me that the default mode of British designers whenever presented with a reasonable sized room is to ignore most of the useable space. A large proportion of the area is reserved for a fiddle-yard, the operating potential of which frequently outweighs the modelled section, with the ‘on scene’ section encompassing perhaps one side of the oblong and a varying amount of the two adjacent sides. Implicit in this description is the assumption that the layout will hug the walls without ever venturing into the chasm in the middle, irrespective of the area wasted. That, of course, is where the operator stands, isn’t it?  Even within the footprint of the AFK’s room (22’6” by 9’3”) the end result is that perhaps 34 square feet (22’6” feet by 18 inches) of the 208 available (16%) are actively used following these parameters. One might take umbrage with this analysis, but a brief inspection of the realised layouts and the planned proposals, featured in a representative sample of the commercial magazines published during the last twenty or thirty years, will generally confirm this trend. Whilst this format has advantages for an exhibition layout it is a profligate use of space, and by implication money, in a domestic environment.
Space is expensive to obtain so why waste it? This photo shows one aisle with the layout at an early stage of construction. At the left is the (off scene) approach to Fenditavalat on the top level. Centre left is Lacono Cittavecchia on the middle level with Eromarbordo beneath it and not really visible. At the top right Ospicio d' Helcaraxë sits above Boursson.
Relatively small American layouts, shoehorned into the same space, exhibit an almost diametrically opposite approach, with the space being intensively used. It is quite common to find two or three small towns along the route with, in extreme cases, the opposite ends of a passing loop having different names, increasing the apparent number of communities served by the railway. Our US counterparts also view the room’s central area as an opportunity to be grasped rather than a chasm to be avoided. Many layouts incorporate peninsulas wherever possible, with a 180° curve allowing the line to progress upon either side of a central backdrop. Underpinning this approach is the willingness to maximise the visible area of the layout, the fiddle yard often being entirely hidden at a lower level, perhaps only a couple of inches below the main station. Whilst this latter type of layout is not really a double-decked layout it does highlight the different philosophies between the two approaches.
It is interesting to speculate upon the reasons for these differences, although that is not the main intention of this piece. I would suggest that British modellers tend to follow the pattern outlined above because of the influence of the exhibition circuit. Many modellers wish to demonstrate their work at the local show and the hollow oval is what the majority of layout builders see and expect, except where space has restricted the builder to a fiddleyard-terminus arrangement. It is obviously not practical to include a peninsula inside the central well of such a layout or to contemplate more than one deck. The only design criteria that seem to have been debated in recent years are the height at which that deck is situated and, to a lesser extent, how the layout is presented. Such layouts paradoxically tend to be designed ‘inside-out’, in that the most attractive side is presented to a viewer standing outside the layout, rather than to the operator. The owner therefore, by implication, permanently views the backside of the layout when it is re-erected in the layout room at home, although it would seem that many such layouts are never erected between exhibitions, living in a limbo-land of storage boxes in the garage, or where-ever. The construction of exhibition layouts has almost become a hobby within a hobby and the creations of the serial layout builders dominate the pages of the British press. I often wonder how representative of the hobby as a whole such people are because they seem to have had a disproportionate influence upon the printed media and the typical design template.
Multi-level layouts are for home consumption only. There is no chance of exhibiting such a layout as a whole, although there is no reason why certain sections could not be made detachable if the builder wished. The main attraction of the design is its more intensive use of space and the underlying assumption that the layout is built for the builder’s benefit rather than a critical public. Space is expensive to obtain, so why not maximise the potential of that at your disposal? Even if the hidden layer only contains a fiddle yard, this will leave the total visible area of the layout available for scenic treatment. The length of run is also increased, allowing more scenes or more stations to be incorporated, depending upon the builder’s inclination. The other advantage of this approach is that scenes retain integrity, in that the train will not traverse the same setting twice, when these places are supposed to be miles apart.
Jakarutu can be detached from the layout and has occasionally been taken to exhibitions although it does not offer much scope for interesting operation.
Practical considerations: support, lighting and access
The downside of the above arguments is the complexity involved in the layout’s construction. The fact that many multi-level layouts have been built shows that the problems can be overcome but this requires a willingness on the part of the builder to confront them. The most obvious problem to consider is the method used to support the upper deck. In its simplest form this could be done by building it as a conventional baseboard supported by a framework of legs attached to the lower deck. This would, however, have the drawback that the front supports would be visible when viewing the lower level but the problem can easily be solved by supporting the upper deck on the shelf brackets available from any DIY shop. We also need to consider how the lower deck will be lit. Generally speaking this is best achieved by placing fluorescent strip lights at the front of the upper level. One advantage of these fittings is that they do not give off the heat of incandescent bulbs so that there is no fear of them heating the layer above them.
The upper level is simply supported by shelf brackets, in this case incorporated into the sky or.....
.... in this case behind the backscene. This view also shows how the lighting is arranged at the front and the wiring is not visible from normal viewing positions when tidied up.
Koester’s book considers lighting in great detail and, as usual, it comes down to the effect that the builder wants to create. The AFK makes do without lighting for much of the lower level, the room lighting being sufficient. The light intensity reaching the lower level depends, of course, upon the width of the lower level in relation to the upper and the vertical separation between the decks. As much of my run is on very narrow boards and the upper deck is roughly 20 inches above the lower layer, the lack of lighting is not so apparent. Lighting was necessary where stations were placed beneath those on the upper layer. The fluorescents were generally fitted along the front of the layout without difficulty but the restricted access to Eromarbordo forced them to be installed at the back. This is not an ideal solution but as the station is only 30 inches from the floor and the operator sits on a buffet looking down at the scene it is acceptable for operating purposes. The lighting effectively replicates the low angle of insolation usually found in the early morning or late evening of a summer’s day. The placement does cause problems in obtaining photographs, without airbrushing, and is apparent when it is necessary to reach into the scene to uncouple wagons. In the latter instance I am too busy concentrating upon operational practicalities than to worry about the aesthetics.
Having touched upon the issue of vertical separation between the levels, practical experience suggests that one foot is the preferred minimum, with a few more inches being beneficial. To some extent this depends upon the height of the decks, always a thorny problem, because the upper layers impinge upon the sightline of the lower level. In a few locations there are three decks on the AFK, such as where Fenditavalat is stacked above Urteno, which in turn is placed above Relforka. The top level is placed just below my eye-level, which can cause problems in reaching into the scene to couple vehicles located behind wagons parked at the front of the layout. The three-phase overhead wiring exacerbates the problem but by keeping the scene relatively shallow, at three running lines placed in front of the town, and being prepared to temporarily shove wagons out of the way, the difficulties are easily overcome. Similar minor problems have been experienced at Urteno, where operation is carried out either standing up or sitting down, depending upon the view preferred. The lower level at Relforka has created the most headaches, at 30 inches from the floor, because the middle layer restricts the view. As Relforka is effectively a (scenicked) fiddleyard this is not too great a drawback and a reasonable view of arriving or departing trains can be had by sitting on a low chair. At Eromarbordo, situated at the same elevation across the peninsula, the difficulties were anticipated by once again placing the track at the front of the scene, allowing virtually unimpeded access. The fishing boat provides the only obstruction and this is removed, to a specially constructed shelf nearby, whenever shunting takes place on the quay.
This photo shows the problems of lighting the scene from the back and the need to achieve easy access by removing the fishing boat.
Practical considerations: movement between decks
There are other aspects of the layout’s design that must be considered, even in such a basic article as this. The most pressing of these is the method by which trains travel between the decks. Some modellers advocate the use of helices, although there are many disadvantages with these, not the least being their complex construction. They also eat layout space and hide moving trains for a long time, thus needing careful evaluation if they are to be included in the design. I have no experience of these devices as the AFK employs the alternative principle of treating the whole layout as a helix. The track rises from the platform of Relforka and climbs all the way to Ospicio, creating an effect similar to that of a giant corkscrew. The general advice pertaining to this approach is to keep the stations flat so that vehicles do not run away in the sidings. I would second this advice but, being unable to follow it in all locations, I have had to employ various braking and scotching devices at some stations. Alternative options are available to transfer trains between decks if one is prepared to sacrifice the ease of simply running a train along the line. Iain Rice illustrates a basic multi-level scheme using bookshelves with the trains being lifted between levels on a cassette. [2] A more sophisticated version of this idea was explored by Peter Denny who used a 'train lift' constructed from Meccano on one of the early Buckingham layouts. [3] The idea was reprised recently by Jas Millholme on his Yaxbury branch in S scale. [4] In essence the train runs onto a moveable piece of track, stops and is then transferred between levels by a mechanism rather than climbing or descending a slope. Some degree of automation is implicit within the concept so that the operator can focus upon running trains rather than worrying about running a train off the end of the track if the lift is not in the correct position. I can see no reason why a simpler version would not work providing that care was exercised in its use.
In order to obtain the gradual rise in the roadbed of the round the walls spiral the ability of the motive power to pull trains up gradients and around curves needs to be factored into the calculations. Given the larger spaces and longer runs available to US builders it is possible to have gentler gradients between the decks in addition to larger radius curves. The lack of such long runs meant that the AFK’s ruling grade is 1 in 36 and also explains the gradients in the stations. The perimeter of the room works out at approximately 62 feet, or fractionally over 20 yards, and the run between Relforka and Lacono traverses this distance. Using the specified ruling gradient would therefore allow a maximum vertical separation of 20 inches but roughly 9 yards of the run is to be found in stations. The gradient in Boursson was reduced to 1 in 72 to obtain the 12 inch climb and it is difficult to park free running stock in the sidings. Such a steep slope and the relatively sharp two foot curves employed, do not look out of place in the context of a narrow gauge railway traversing undulating terrain, but would be more difficult to justify in the context of a mainline standard gauge layout crossing a plain.
The layout is built as an extended helix. the bottom level is visible on the right with the second level climbing above it The rack branch at the top left is descending to meet the second level at the junction in the distance.
The sharp curves and steep gradients also impact upon train lengths and speeds. Train lengths are limited on the AFK by the capacity of the loops, the shortest of which are set at 8 four wheeled wagons excluding the locomotive and crew van. Longer trains are run but this may necessitate using what Americans refer to as a 'saw-by' for them to pass each other. The motive power uses standard HO mechanisms from the more reliable manufacturers, such as Fleischmann, and has so far proved robust enough to stand up to the demands of the layout whist giving the smooth slow running required on the narrow gauge. The use of feedback controllers helps in this respect. I am a little concerned by recent developments of these manufacturers who seem to have moved towards more finely realised HO/OO running gear at the cost of increased delicacy in the finished product. The older mechanisms have proved capable of handling the trains, although many have had extra weight added during their conversion to accept new bodies. On the other side of the coin, the rolling stock is heavier than its HO/OO counterparts so I would not envisage too much difficulty in running 6 or 7 foot long trains in the smaller scales, using commercial equipment. Whether it would be possible to regularly pull such trains up similar gradients using the handmade mechanisms demanded by EM or P4 standards might be a different issue and the curvature required by the site would almost definitely preclude a P4 layout, even on a single deck. Perhaps this is another contributory factor to the large oval designs common in British modelling or the development of the forty foot long straight exhibition layout where the small scenic section is swamped by two vast fiddleyards. Running speeds are relatively slow, as might be expected from a narrow gauge line, although an HO/OO mechanism would cover the same distance in the smaller scale in the same time and, hence, would be travelling twice as fast, in scale terms. Even so, I would not have thought that it would be easy to exceed 35 to 40 mph in 4mm scale on the 1 in 36, although this would probably be faster than that which steam powered prototypes could manage in similar circumstances.
The unfinished mallet tank is based around an old fashioned Mantua product mechanism bought years ago. This version had all metal valve gear whereas later versions, I believe, used plastic parts.
Practical considerations: operation
One other area demanding some thought before deciding upon a multi-deck’s viability would be the intended method of operation. Underpinning the large US layouts, almost without exception, is the assumption that the layout’s operating sessions will host numerous modellers. It is not uncommon to read magazine accounts stating that eight people is the minimum operating crew and that sixteen can easily be accommodated, with things beginning to get crowded at twenty. The allocation of an engineer and conductor, or a driver and guard in the British context, to each train, accounts for these large numbers. Once yardmasters, dispatchers and station agents have been included, their nearest British equivalents perhaps being signalmen and the control office, the count rises. The US layouts therefore recommend wide aisles between the sections of the layout but experience with the AFK, which is operated single-handedly, has shown that these are not necessary. Similarly Koester's suggestion that two towns, stacked vertically, require their operating foci to be at opposite ends to avoid the operators at the different locations getting in each other's way is irrelevant to a single man layout.
Finally, to conclude this brief overview, as in many other aspects of railway modelling, layout design is an exercise in compromise. One of the less remarked aspects of such is the time span within which it is envisaged that the layout will mature. Given the reliance placed upon scratchbuilding and the precedence given to running sessions it was realised from the outset that the AFK would take many years, if not decades, to reach fruition. In practical terms this ‘long haul’ approach means a resigned acceptance of living with inaesthetic swathes of bare plywood, incomplete scenery, mocked-up buildings and exposed wiring rather than a finished layout. Committing to such a project would obviously not suit someone who wished to see quick results or who anticipated moving on to another modelling subject within a few years.
A large layout means living with exposed wiring, building mock ups and  bare baseboards.
This is the same scene about five years later. It is still incomplete but progress has been made. Twelve years into the project many areas remain in a state similar to that shown above.
At the end of the day I feel that the complications of the multi-level system were worth it. I did, however, wish from the outset to build a model of an entire railway rather than a small slice of a railway, such as a station in isolation. Operation is also a key plank of the AFK and at certain times of the ‘day’ there can be a dozen trains and shunting movements taking place ‘simultaneously’ in as many as eight different locations. If you wish to build the archetypical bucolic wayside station then the approach probably has little to commend it. If there is the space and the desire to build a complex system then the multi-level design may be the answer to your problems.
1. Designing & Building Multi-Deck Model Railroads, Tony Koester, Kalmbach, Waukesha, 2008.
2. Small, Smart & Practical Track Plans, Iain Rice, Kalmbach, Waukesha, 2000.
3.Peter Denny's Buckingham Branch Lines Part Two, Peter Denny, Wild Swan Publications, Didcot, 1994, p169 et seq.
4. Model Railway Journal No 167
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