(28-07-2010, 10:20 PM)Archie Wrote: Does anyone know of any literature on axle counters, particularly the ones produced by 'THALES' installed on the NLL project, and in particular the testing process of these.1. Not much that I can post.
On another note, over the last couple of weeks, and maybe coincidently that I have heard it off a few different people, will axle counters take over from track circuits eventually, certainly 'new works' anyway, due to costs and up-keep of TC's over axle counters, but what about on the other hand of not being able to detect things like broken rails etc, I don't know I am just a 'fly on the wall,' but I would certainly like to hear other people's thoughts on this.
If you have access to NR Standards then try for things like NR/SP/SIG/10129, NR/GN/SIG/11900, RT/S&S/IRM/FTA/07.....
At Railway Group Standards level which are available to download (often best just to Google the reference number) then GK/RT0217 and GE/RT8217 spring to mind but these might well have further cross references within. However these probably aren't quite what you want and are more "module 1/7 ish" than directly useful for module 5.
NR decided to go for axle counters in a big way I suppose 10 years ago and the first big manifestation of this was the West Coast Mainline Route Modernisation. Like all things on the railway things take time and yes it is only in recent years that one assumes that all new works will feature. They are not an unmixed blessing however so there is some "rear-guard action"; probably the truth lies somewhere between the two extremes and it is "horses for courses"; some applications are better served by conventional track circuits and others by axle counters. One of the issues is certainly the overcomplicated manner in which we reset/restore/impose aspect restriction etc after a miscount in an attempt to mitigate against the signaller doing so inappropriately. Perhaps things are moving on that to ease things- we'll see in the next year or so. At present for a complex interlocking some 30% of the testing time is said to be work i/c/w axle counters resetting etc and for simpler sites where the remaining testing is easier it can approach 50%; truly a case of the tail wagging the dog. On the other hand, read the accident report into the 1991 Severn Tunnel collision and recognise just what a severe disaster this could so easily have been.
I attach pdf of presentations that we used some years ago, one of which is large so have split into 3 portions. This latter one is I believe reasonably self explanatory but remember that they were both really designed to be talked through rather than being viewed in isolation but I think that the pictures and diagrams may help.
PJW