2020.02.18 Cambrian track layouts

The most fundamental part of a simulation is probably the track layout, and getting it right is often the hardest research task. Taking the Cambrian Railways project as an example, we have the following resources available:

1. Historic signal box diagrams
2. Contemporary notes by railway staff
3. Track plans in books
4. Photos
5. Old large-scale maps
6. Accounts of contemporary train working
7. Present-day examination and measurement

Sadly not all of these are dated, and they don't always agree.

Taking Aberystwyth as an example, a signal box diagram from around 1950 exists, though not dated. Unfortunately signal box diagrams usually do not show unsignalled lines, so there is no detail of the shed or goods yard.

We are fortunate in that one John Swift, who had wide-ranging responsibilities covering the then London Midland Region in the late fifties, left his notebooks to the Signalling Record Society, and much of their contents have been published as a series of books. They contain fairly detailed track diagrams covering almost everywhere within his area, often including lever numbering and local names for some lines. In the case of Aberystwyth this does cover the shed and yard areas in detail.

There are some very good books around, and Aberystwyth features in Volume 1 of "The Coast Lines of the Cambrian Railways". A plan is provided that includes more detail of the goods yard, including local industries and names for some of the sidings.

Sadly most photos seem to concentrate on passenger traffic, generally on the move, but occasionally photos do answer questions. In this case some detail about the use of sidings came from photos, largely in the above book.

While not useful in this particular case, I should mention the availability of old large-scale maps from the Scottish National Library. The coverage of Scotland is comprehensive; most of England is covered, but Wales less so.

It would be nice if people at the time had written accounts of how traffic was actually handled on an everyday basis, but finding that sort of information is rare. One source may be available: local signalling instructions, and notes in the relevant Sectional Appendix to the Working Timetable. The latter did yield instructions for dealing with traffic to Aberystwyth Gas Works.

Finally, sometimes there's no alternative for seeing for yourself. I was able to pace out the length of the old platform 3 at Aberystwyth, and a quick look from the train window at Caersws finally enabled me to make sense of the original track layout there.

Having worked out what the actual track layout was, we usually have to make some compromises when designing each screen. In the case of Aberystwyth, the plan can't be to scale, but we do seem to have just about everything fitted in, and all prototype movements are possible.