Track Circuit failing to "Fail"

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Track Circuit failing to "Fail" 24/12/2013 at 08:30 #53145
indian_railways_fan
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72 posts
I have an obscure bug at KX.This is the modern era.


I have a track circuit failure in the section marked out with the yellow line portion.As 5Y52 was ready for departure,I reversed the point 2031 manually through F11 menu and authorized the train past the signal.Now it will occupy the very next TC(TKNE)past the signal and then it should occupy the next TC(TKBL).However what happens is that this track relay dropping is not indicated on the panel and instead the train directly appears at the TC(TKBK),presuming it has also occupied the already failed TC(TKBL).

At first I thought it was a bug but it probably faithfully represents what would happen in a real interlocking system where the picking up of the sub-route setting relays will also ensure that only the correct route strip lights will display on the panel.As in this case the sub-route has not released over track TKBL,the track occupation will only be indicated for the route which is already set.

Khalid.

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Track Circuit failing to "Fail" 24/12/2013 at 10:15 #53146
JamesN
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1570 posts
While it looks odd, as you say that is the correct behaviour. Sub-route locking defines which 'legs' of the TC should show occupied, while handcrank overrides which direction train goes.
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Track Circuit failing to "Fail" 24/12/2013 at 12:00 #53151
Stephen Fulcher
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2007 posts
Essentially your explanation is correct. SSI, upon which SimSig is based, behaves for the most part in the manner you have suggested, or certainly all the ones I have seen do (as someone is bound to have seen something else!!!).

Subroute locking in RRI is actually done by the relays dropping (ie they pick up to clear the route and drop away to lock it). This is therefore fail safe as a power failure or other fault such as a defective contact will cause the relays to drop and routes become locked, rather than the relays drop to free up a route with trains on it.

If a route is set over a track circuit and that track circuit shows occupied for any reason, then only the portion of the track circuit that applies to the route set over it will show occupied.

In E10k relay interlocking, if you lose correspondence in the points (which means they are no longer detected in the same position as they have been called), which will happen if you handcrank the points, then the route cascade could end up going both ways from the set of points depending on the installation, and the track circuit indications could do all sorts of things, again depending on installation.

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