ARS regulation issues

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ARS regulation issues 31/01/2014 at 10:21 #54692
Jan
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I know that ARS isn't supposed to be perfect, nevertheless I've seen it perform some strange regulation decisions even though both trains concerned were running on time.
In some cases I've managed to catch ARS in the act so to speak, and take a closer look. After blocking off further route setting by placing reminders, I've taken a look at the ARS routesetting status.

Normally, I would expect one of the trains to be showing as "Giving priority to ...", however in all cases, strangely enough both trains were simply showing "Waiting for route to become available", as if ARS wasn't even aware that there was a conflict - which would at least explain why it was setting routes in a first-come, first-served fashion.

I've seen instances of this occurring in at least the following locations:

  • Streatham South Junction: between Thameslink trains from Wimbledon towards Tulse Hill and Victoria - Epsom / Epsom - Victoria trains, e.g. 2O42 vs. 2E37, and then afterwards 2O42 vs. 2E40.

  • Streatham Common: ECS from the Tulse Hill direction towards Selhurst (via the Streatham Spurs) and regular trains from Victoria on the Slow Line. ARS sends them in the wrong order through Streatham Common.

  • West Norwood Junction: trains from Streatham Hill to West Norwood vs. trains from West Norwood to Tulse Hill, e.g. 2F18 vs. 2H76.

  • Tulse Hill South Junction: trains from West Norwood to Tulse Hill vs. trains from Tulse Hill P4 to Streatham, e.g. 2H78 vs. 2J37. In this instance, the overlap from VC770 is already blocking the junction, so I would have expected ARS to either select the warner route from VC716, or at least to be "Giving priority [in overlap ?] to ...", however again, both trains were simply "Waiting for route to become available".



I've also observed some wrong regulating in the Sutton area which might be related, however as of now, I've only ever noticed it when it was already too late.

Another problems concerns Bromley Junction. Here, West Croydon - Victoria trains are booked to run just in front of the trains from Beckenham Junction. As there is very little advance notice of trains entering from Norwood Junction, by the time that train enters, ARS often has already set the route for the Beckenham train. Might it be possible to delay setting that route until the train has left Birkbeck and is actually approaching signal VC746?

And finally, not really a grave problem, but interestingly just the opposite of the first one, so I'll mention it just in case, a train giving priority even though it needn't to. This happens to ECS trains from Tulse Hill to Streatham Hill Shed, which are held at Leigham Junction for a 2Sxx train
a) which is still somewhere in the Crystal Palace / Gipsy Hill area
b) and even though both trains are running on time and the ECS train is scheduled to go first

Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick.
Last edited: 31/01/2014 at 10:41 by Jan
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ARS regulation issues 31/01/2014 at 12:39 #54704
DriverCurran
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682 posts
Jan

I think (not got access to the WTT at the minute) that in the WTT 'Read Me' text file, that there is mention of the fact that the ARS is a bit trigger happy in the Streatham Junction area, the same also applies to the 2Nxx services at Battersea Park.

Would have to have a run through of the timetable to look at the others.

Paul

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ARS regulation issues 31/01/2014 at 13:15 #54707
Jan
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Ahh yes, I remember reading something somewhere about ARS problems, but then couldn't find it again because I was only looking in the manual and had completely forgotten about the timetable notes. Thanks for the reminder.

At Battersea Park I'd say the problem is more akin to the issue at Bromley Junction because you - and the ARS - get very little advance notice about SLL trains, however I usually manage to place a reminder or cancel the route from Clapham Junction in time, and once both trains are present, the train approaching from Clapham Junction correctly shows "Giving priority in overlap to 2Nxx".
Around Streatham the problem seems to be of a different nature, because even though both trains are present - and usually have been for quite a while - somehow ARS doesn't realise there is a conflict between them.

Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick.
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ARS regulation issues 31/01/2014 at 13:29 #54708
JamesN
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As Mr Curran says, I wrote a "Timetable Notes" file, which I think was included in the installer, which does highlight a lot of the ARS foibles I found when writing the TT. It's in .../Simsig/Timetables/VictoriaC/...

ARS can only regulate for trains that it can see - this causes particular issues at Bromley Jn where to satisfy the 2 greens rule ARS will set the route long before the train leaves Birkbeck, but a train may enter from Norwood Jn in the intervening period requring the junction first. There is no way the ARS will know about a train before it's entered, therefore there's no conflict for it to manage. The real-life Victoria Signallers have better information at their disposal in that regard, and they also have the benefit of running the TT every day; knowing that the 2Sxx always goes ahead of the 2Hxx and so on. Limiting the ARS to only set the route at such and such a time would fix it for this Timetable, but a previous years' timetable I looked at had them 12 minutes apart, and thusly ARS would be holding trains up from Beckenham unecessarily. You have to be very careful about 'fixing' ARS to make a particular timetable work, because you could potentially, inadvertantly be breaking one from a previous or future date.

I always play any ARS sim with the addage in the back of my mind that ultimately it is my 'job' to ensure the trains are signalled and running in the right order. ARS is there to help me where I need it, but I shouldn't be left alone to make decisions.

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ARS regulation issues 31/01/2014 at 13:48 #54712
Stephen Fulcher
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Best option in this case may be to turn off the ARS for the junctions concerned and route them manually.
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ARS regulation issues 31/01/2014 at 13:54 #54713
Jan
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Yes, I know that ARS can only regulate trains it can see - which is why I'm a bit puzzled about the behaviour in the Streatham area.
You've convinced me about Bromley Junction though, you have a point that introducing timetable-specific fudges wouldn't be the best of ideas.
I do try to keep an eye on the whole area, and off-peak most of it can be run manually, however in the peak and/or with added failures and delays, things can get a bit manic...

Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick.
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ARS regulation issues 01/02/2014 at 14:34 #54782
Jan
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After a bit of further playing, I can add Streatham North Jn and Balham Jn to the list, however only in the Up direction. E.g. there is no regulation at Balham between trains approaching on the Up Brighton Slow and the Up Crystal Palace, however conflicts between trains on the Up Crystal Palace and the Down Brighton Slow are regulated.

Strangely enough, even though regular trains don't get properly regulated at West Norwood Jn, one of the 5Zxx ECS moves from Three Bridges to Bedford actually got held at West Norwood Junction "Giving priority" to a regular train on the Down Crystal Palace.

Likewise, one of the 3Sxx sandite workings (3S92-7) did receive at least some amount of regulation through the Streatham area (it was held for a Thameslink train on the Up Portsmouth), so it seems that ARS is not completely broken at those locations.

Edit: Scratch that, even in the down direction, I occasionally - but not always - get unresolved conflicts both at Streatham North Jn and at Balham Jn. Conversely, from time to time regulation does work in the Up direction as well, so no clear pattern discernible.

Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick.
Last edited: 01/02/2014 at 20:02 by Jan
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