2002, 2006 Point Control Table

[sugavanam nagarajan]

Please review 2002, 2006 point control table and suggest the areas to be improved.

-Sugavanam

[Peter]

Please review 2002, 2006 point control table and suggest the areas to be improved.

-Sugavanam

I have not got the 2002 layout handy so have only had a look at 2006.

2006 225 points

Not a bad effort as far as I can see. We agreed on just about all of the relevant routes except that you chose to have quite a lot of swinging overlaps meaning that you had opposing route entries for 173A(M) W 228R; 171A(M) W 228R; 122 A(M) w 222R. You appear to have got the entries right, but the relevant signals do not explicitly have swinging O/L. Others may differ in their opinion on this, but stating which ones obviously do and chosing which ones don't where there is not explicit evidence of it would save you some time.

You do seem to have got confused where the lase entry in N>R for "set by" is concerned - you have 122A(M) w 223R, but 223 are nothing to do with 122A(M) and in the corresponding entry for "requires" for R>N you have [122A(M) or 222N] but that combination would want 225N so would not lock them form going N

Releases for 122C(S) adn 124A(S) do not go as far as the overlap (CL) and you have used the track beyond the signal (CN) for the time off instead of the berth track (CP) and have CN in there twice.

On a similar subject, there are several places where there are two tracks in the on the approach to the signals which have the points in their overlap and you have only used one of them for the timed release eg for 122A(M) you have AB clear and [AC clear or occ for time] - the platform is 350m and the train is 200m and so is likely to occupy both tracks when it approaches 134 and with your controls, the overlap will never time off.

234 points

Look at the tracks you have included for timing off the overlaps from 138 and 134 signals again (same comment as above).

You have included several other point conditions in the deadlocking tracks, but you are explicitly given some of the clearance points. Have a look at the discussion by PJW in relation to 2004 CT on this matter

In general, you have also not consistently either included or excluded the dead locking track from the route locking release. I have heard arguments both ways on this one, so would welcome some comments from people cleverer than me on this topic - should deadlocking tracks be shown to be required clear in the route locking release?

Peter

[PJW]

In general, you have also not consistently either included or excluded the dead locking track from the route locking release. I have heard arguments both ways on this one, so would welcome some comments from people cleverer than me on this topic - should deadlocking tracks be shown to be required clear in the route locking release?

IT DEPENDS ON YOUR STANDARDS!
Basically in RRI I'd expect tracks up to but EXCLUDING dead locking tracks. If the point is locked by the track anyway, the route locking (even if it actually exists) is not shown on CTs as it adds nothing.

In SSI there is (almost always) track bob protection; i.e. if track becomes clear unexpectedly (e.g. rusty rails) then the route locking holds for 15 seconds since it does mitigate risk of loss of train shunt. Particularly important where Automatic Route Setting is provided, since computer would take advantage of apparent route availability whereas the human would hopefully stop and think: "where is that other train?"
Hence in this case there is ADDITIONAL locking after the track becomes clear after route has been set, as compared to just the track itself without any route being set. Hence for SSI then show route lockig INCLUDING the dead track. However even in SSI only provide such locking for the "post-to-post" route but not the overlap portion, so therefore for the overlap then again it is route locking EXCLUDING the dead track.

It really does not matter what standards you adopt, BUT DO BE CONSISTENT. Also be consistent within your group of Control Tables- for example if you decide to give shunt routes overlaps when doing the "route and signal", do make sure that when doing the point CTs that you also give shunt routes overlaps.

A real big give-away that you don't know what you are doing is where you produce CTs of two elements which interlock each other and you do the two inconsistantly- e.g. decide a particular set of points is called flank by a specific route when writing the point CT, yet failing to call that very set of points when writing the CT for that specific route!
This either demonstrates "carelessness" or "complete lack of comprehension", neither of which is a good impression to create on the examiner