Signalling problems at Clapham Junction affecting South West Trains

[DY444]

More than likely relay interlocking. I'm sure software is SSI?


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Yes the others are Relay Interlockings.

In very basic terms an SSI is a processor (and hence software) controlled interlocking with its control tables defined by data.

 

[infobleep]

I do not doubt your point of view, however you get a different view when you are a regular commuter; if you don't encounter problems in the moring, something is likely to happen in the evening.

I disagree about the problems occurring daily. Yes you will probably end up on at least one train this is either slightly late leaving and/or arriving but that's usually about it. Nothing major in the grand scheme of things.

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[Muzer]

Yes the others are Relay Interlockings.

In very basic terms an SSI is a processor (and hence software) controlled interlocking with its control tables defined by data.

Ah, OK. So is interlocking using just electronics (ie transistors) actually a thing, or did that never exist?

 

[Olaf]

I disagree about the problems occurring daily. Yes you will probably end up on at least one train this is either slightly late leaving and/or arriving but that's usually about it. Nothing major in the grand scheme of things.

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I disagree; the problems are occurring daily. I would also point out that on suburban services, the delay is not counted unless the train is more than five minutes late at it's destination. When the delay is acknowledged, it is attributed to the same root-cause.

 

[Tomnick]

I disagree; the problems are occurring daily. I would also point out that on suburban services, the delay is not counted unless the train is more than five minutes late at it's destination. When the delay is acknowledged, it is attributed to the same root-cause.

Delays are investigated and attributed if more than two minutes (against WTT timings) are lost over any reporting section, or if a smaller delay causes the delay to another train to exceed that threshold, or even less delay in some areas. That's completely different to a train failing PPM, which does require a suburban train to be at least five minutes late at destination (against public timings?).

 

[infobleep]

Out of interest, how many minutes late does a train need to be before the company responsible has to pay one or more of the other companies compensation. Is that also 5 or 10 minutes?

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[Tomnick]

That's all based on the delay attribution I described above, so rather more stringent than the thresholds for PPM. It's far from simple though!

 

[Pumbaa]

Out of interest, how many minutes late does a train need to be before the company responsible has to pay one or more of the other companies compensation. Is that also 5 or 10 minutes?

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3 is the threshold. All delays are still tallied and counted, and go in the big 'sub-threshold' pot, which they all (proportionally) chip in for. I don't know if that's the same as other routes, or if the rules are nationwide.

Edit - a quick google and a glance at the IIP suggest it's nationwide.

 

[infobleep]

Thanks for the interesting replies. So I know if a train is more than a minute late passed a monitoring point, some company likely being finned.

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[Pumbaa]

In a word, yes. Although perhaps it's best phrased as 'someone somewhere pays for any delay'. A delay less than 1m is not a delay, as Trust can't tell the difference!