Safety Assurance in Interlocking Design

I use the term interlocking here as it is used in the railway signalling community, as a noun; the term is synomonous with signal control system, and rather shorter to write down. My thesis (for want of a better word) is about guaranteeing that these formidably complex finite state machines are `safe' in some sense.

As I recall it begins something like this:

This thesis presents a study into the application of theoretical computer science to problems arising in the railway signalling industry. [...] The technical material in this thesis is presented in a style which, it is hoped, is sufficiently transparent to be intelligible to practising engineers seeking to emulate the study. This introductory chapter covers much of the background needed to establish an intuitive framework which later chapters will build upon more formally.

I suppose I should point out that I'm thinking of Computer Systems Engineers here, rather than Railway Signalling Engineers per se, although amongst the latter community there is definitely an ongoing shift in the skills base towards CSE. Whether I succeeded in this adventure I don't know since there is, as yet, no way to please everyone: for some this work contains far too much verbiage and far too little in the way of hard sums; for others there will inevitably be a great deal of mathematical psychobabble to read through. Sorry. Anyway, the Introduction is broken down into digestable chunks as follows:

1.1 Quite a bit of motivation
1.2 A whistle-stop tour of railway signalling
1.3 Solid State Interlocking (eminently skippable technical bits)
1.4 Inter-SSI communications (eminently skippable technical bits)
1.5 An overview of some related work, and the rest of this work

No way am I'm not putting the whole thing up here in hypertext. You can get hold of a nicely printed copy from <> in Edinburgh, or you can also download the PostScript file to print yourself.


Matthew Morley, Edinburgh. Date: 29 November, 1998