Peter Howell, my collaborator on Grindham, is a very enthusiastic builder of structures and scenery and the requirements of a shed scene present some considerable challenges in that area and so, with the retirement of Grindham, we decided to embark on a new layout to be based around a running shed. Given the existing stock of locomotives, together with our predilection for things Great Western, a GW area shed was inevitable; that it should be Grindham Shed, entirely predictable.

Careful planning would be essential to ensure that we achieved something that would not only follow prototype practice, but also accommodate the various locomotives, including large 4-6-0 and 2-8-0 types. As the layout would be built to P4 standards, and all the track would have to be hand built, careful planning and design would be especially important; P4 can be very unforgiving! The stages we went through are documented below.

P4 is not everyones' cup of tea, but the stages and processes described here are equally applicable to any model, irrespective of gauge and scale

The drawing shows the board outlines, which delimit the available real estate. The dimensions are in inches - I am too long in the tooth to think in metric! CAD makes it an easy matter to convert to metric when the need arises - another great benefit.

Using the trusty CAD package, the floor plans were drawn to scale, with track centrelines included to assist with proper alignment at a later stage as can be seen in the accompanying illustration.

Another advantage of CAD is that the drawing can be built up in layers so that things such as the dimensions and labels can be kept separate from the outline; this makes it so much easier for subsequent use, where details other than the drawing itself would be spurious.

This drawing of the floor plan has the dimensions in millimetres; this is in preparation for use with some clever software for drawing track which we will meet shortly.

Further scale drawings will be required in due course for construction of accurate models of the structures, but we are a long way from that!

By adding vertical lines at 100mm intervals to represent supports, the CAD package was then used to read off the dimensions of each support for use in subsequent construction. The process was repeated for the 100 ft (400mm) at 1 in 80 beyond the stage.

The whole "turntable" can then be rotated on screen and the track with the centre-line used to align potential approach tracks.

This drawing was combined with those of the shed and coaling stages and the baseboard outlines so that preliminary designs of the shed area could be made.

The drawing is a very early sketch of the proposed layout and, although it differs significantly from the final design, it nevertheless incorporates all the main features - the 4 road straight shed, the coaling stage with ramp and a 65ft turntable. The scale "footprints" of the structures were essential to ensure that they fitted in; use of CAD means they can easily be moved around and repositioned while various ideas are tested. You may have noticed, for example, that the shed here has been rotated through 180 degrees from the original CAD drawing and the turntable rotated about its centre to align a potential approach track.

Limitations on practical curvature meant that one idea, for a hidden track from the unused board to the shed, proved impractical and had to be abandoned. This board has been set aside for scenic development and will feature an urban scene to help put the shed in context.

Templot not only generates a template for any conceivable piece of track, it also allows the shapes of baseboards and structures to be included; these can be drawn using Templot, or imported from CAD or from scanned drawings. This makes it easy to align tracks with structures and to check for adequate clearances as well as the all important consideration of whether the track will fit in the space available

Templot costs less than most ready to run locomotives, and is a very worthwhile investment. Usual disclaimers apply - I have no connection with Templot other than as a very satisfied customer. To find out more, go to the Templot web site.

Although not obvious here, the turnouts have correct Great Western style curved switches - the assumption being that under BR ownership any renewal at a shed would have re-used recovered GW track rather than new items following the REA practice adopted after nationalisation. Note the sleepers have been omitted from the shed roads where there will be inspection pits, and the ash roads where there are also pits and the area will be paved.

Templot also enables movement of the structures to the desired location and orientation - you can see, for example, that the shed, originally drawn in DesignCAD, has been rotated slightly from the horizontal. The track centre lines from the original CAD drawing have been used to align the shed roads. The turntable was re-drawn using Templot instead of the original CAD version; this ensured precise alignment of the approach and exit tracks with the turntable bridge.

When the templates are printed out full size, they are used as the basis for building the track. The templates are fixed accurately in situ on the baseboards so that construction can begin; additional copies of templates can be printed to allow construction of point and crossing work to be undertaken at a work bench, for subsequent installation at the appropriate location

This is the final plan for Grindham Shed. This drawing has been derived from the detailed track templates generated using the Templot software. The track outlines have been re-exported from Templot back to CAD in preparation for more detailed planning of the scenic areas, although the "empty" scenic board has been omitted from this illustration.

As you can see, it differs significantly from the initial CAD sketch. This was due to the need to accommodate prototype switch & crossing geometry and curvature limitations, and also for practical considerations such as physical access to the various parts of the layout. It has only been possible to fit in part of the shed area; the entry to the coal stage incline and the run round loops for coal and ash wagons have been omitted, as have the storage sidings normally associated with a large running shed.

This drawing has had key dimensions added; these are to ensure the track templates can be accurately positioned on the baseboards.

The extended track plan was, again, drawn in Templot and exported to DesignCAD. The different elements (track centre line, rails and background shapes) are in different layers and a new layer for "scenery" will be used eventually to plan roads and so on.

The accompanying drawing shows only the track centre-line for clarity. The red outline delimits the model, and the additional scenery board has also been omitted

I have included a scale to indicate the actual distances involved if this were a real location.

Here you can see part of the plan, roughly laid on top of the baseboards, with Churchward 47XX Class 2-8-0, No 4701, positioned on the turntable. This is the longest engine in the fleet - it is a tight squeeze but, if the Great Western could manage it, we will have to follow suit!

Some of the full size Templot track templates can be seen; these give a clear indication of the correct position for the rails and timbering; not visible is the additional information provided, such as the location of rail joins, switch drive units and so on, not to mention the all important guide marks to ensure correct alignment of the individual sheets of paper with adjacent ones.

Some adjustments were required, such as the position of the turntable to allow easier access, before the plan was finalised.