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Post by superteacher on Oct 20, 2017 18:29:06 GMT
Chaos on the line this evening as all Bank trains are being reversed at Tooting Broadway. Bank and Kings Cross reportedly closed due to overcrowding.
No idea why they couldn’t run more trains by reversing some at Kennington via the siding.
Anyone know more about the nature of the problem?
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Post by goldenarrow on Oct 20, 2017 19:48:30 GMT
Chaos on the line this evening as all Bank trains are being reversed at Tooting Broadway. Bank and Kings Cross reportedly closed due to overcrowding. An unfortunate toxic mix this evening with the Piccadily service getting a kick in the stomach due to a signal failure at Arnos Grove just before the evening rush hour. Any passengers in zone 1 who attempted to make alternative routes were fenced in with the disruption on the Northern having its fare share of ripple effects. I guess the priority for controllers was to keep as many trains working as close to their destinations as possible. The balance between getting services back to their booked slots versus the as many trains+people to the furthest destination scenario is an unenviable task placed on the controllers that are under considerable pressure on all fronts. |
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Post by MoreToJack on Oct 20, 2017 20:16:36 GMT
Signal Systems Failure generally relates to the overriding system - i.e. the Vehicle Control Centres, or VCCs, rather than the cables - but what you see via the public channels is often, at best, a warped version of the truth.
Certainly given the area of the failure it wouldn't surprise me if it was a problem with the VCC at the end of the line (I forget the number...).
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rincew1nd
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Post by rincew1nd on Oct 20, 2017 20:26:30 GMT
...but what you see via the public channels is often, at best, a warped version of the truth. "A good service is in operation..." |
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Post by MoreToJack on Oct 20, 2017 20:28:48 GMT
...but what you see via the public channels is often, at best, a warped version of the truth. "A good service is in operation..." Don't I know it. Last Sunday, no trains on the west between KX and Hammersmith, and no movement on the east... "Good service", they proclaimed... The service status matrix is very much for people watching from afar and gathering statistics, rather than those actually travelling. To bring it on topic, KX today had station control and exit-only operation in place a good few hours before admitted on the Twitter feed... |
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Chris M
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Post by Chris M on Oct 20, 2017 22:59:51 GMT
I was caught up in this attempting to get from Archway to Bank. The first train arrived nearly 20 minutes after the previous one apparently (I was only waiting 12 minutes) and was so rammed I couldn't get on. The second, about 6 minutes after that similarly so. The third train, another ~5 minutes after that was the first one in a long while heading via Bank, but I did manage to get on board (I got a particularly sharp elbow in the back at Kentish Town though). This was all "minor delays" officially.
The member of staff on the platform at Archway was being very helpful (the balding chap with a Scottish accent if any of you know the staff in that area) and knew his local bus routes and where to catch them. I've sent a positive feedback via the contact us so hopefully he'll get an official thank you.
The train I boarded was advertised on both the DMI and on the train as "Morden, via Bank". At most stops the driver was advising that the service was suspected south of Tooting Broadway but she hadn't been advised of an alternative destination so had to assume the controls hoped the problem would be resolved by the time the train got there, but would let us know of any changes in plan when she did. This was still the case even while I was fighting my way onto the platform at Bank (what part of "let the passengers off the train first" is so difficult to grasp?).
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Deleted
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Post by Deleted on Oct 20, 2017 23:07:42 GMT
Certainly given the area of the failure it wouldn't surprise me if it was a problem with the VCC at the end of the line (I forget the number...). I believe it's VCC1, Morden - Stockwell. |
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Post by superteacher on Oct 21, 2017 0:12:43 GMT
The problem was that the service frequency to Tooting Broadway was constrained by the time it takes to reverse trains via the siding. When the problem first occurred, they had a huge queue of trains to turn there. Obviously, they needed to thin the service, so some trains were stabled early. After that, the service frequency provided via Bank to Tooting was insufficient to cope with demand, as Chris M’s experiences show. Having a few extra trains reversing at Kennington would have taken the pressure off slightly in the central area.
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Post by jamesb on Oct 21, 2017 0:58:04 GMT
So in this situation, would trains run through the affected area in restricted manual mode? A through service was restored (prior to a failed train at Tooting Broadway a few minutes ago) but with severe delays - with a plan to suspend the line between Tooting Broadway and Morden for emergency engineering works between 03:00 - 04:00
Does this mean that trains would have to run in restricted manual mode for the whole section controlled by the affected VCC?
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North End
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Post by North End on Oct 21, 2017 2:22:14 GMT
The problem was that the service frequency to Tooting Broadway was constrained by the time it takes to reverse trains via the siding. When the problem first occurred, they had a huge queue of trains to turn there. Obviously, they needed to thin the service, so some trains were stabled early. After that, the service frequency provided via Bank to Tooting was insufficient to cope with demand, as Chris M’s experiences show. Having a few extra trains reversing at Kennington would have taken the pressure off slightly in the central area. An utter, utter fiasco from a useless inept signalling system, although today’s Seltrac shambles was at least very well handled by service control, unlike Thursday’s. The problem was an SCS failure at Morden, so basically the whole railway was lost between Tooting Broadway and Morden. I believe the cause was traced to a cable fault. As usual, the system coped poorly with the disruption. A difficulty at Tooting Broadway was trains were being stopped short of the platform with the siding points normal, the failure area starting immediate south of the points. As a workaround they were dragging and dropping each reversing train from Tooting Bec direct to the siding and asking the drivers to drive in PM (in ATO they would have non stopped the platform). So no reverser could leave Tooting Bec s/b until the previous reverser has entered and left the siding. This is why it was taking over an hour to get from Kennington to Tooting, even when the line went to special service with things thinned out. As to reversing trains via Kennington siding, not an option in the evening peak as the busiest section is Kennington to Clapham North. They were already getting terminating trains off the CX branch discharging passengers at Kennington who were being told to leave the station as they physically couldn’t board a train southwards due to crush loading. Perhaps they could have run empty southbound and then in service northbound from Kennington to at least ease northbound crowding. With a special service being put in, crews literally all over the place, and the line not being experienced at implementing special services for historical political reasons, let alone with Seltrac, it probably wouldn’t have been viable to run anything more than they did. In the circumstances service control and the crew depots did a superb job. This is the third Seltrac shambles this week. First a train lost pilot light between Waterloo and Embankment and happened to stop directly over the VCC boundary. A delay of 20 minutes ensued whilst this was ‘resolved’. Then on Thursday the job was up the wall all day due to platform 5 at Golders Green being unavailable due to a points problem. I don’t believe this was Seltrac related, but the system simply could not cope with running trains through the middle. The route is 10 mph for further than when it was pre resignalling, and each following train was not getting a route into the platform until the preceding one was very far south on its way towards Hampstead. So much for the glitzy Thales publicity showing each train smoothly following the one in front! Then each train was stopping on the approach to Hampstead for no reason wasting further time- a known bug with the system which has never been rectified, just bodged. Result of all this was late running over an hour and the service up the wall all day, not helped by some poor attitude exhibited by a couple of people within the control room, further aggravating things. Some serious questions need to be asked about the capability of the Seltrac system in its current state. There’s no way the line will be able to take a more frequent service based on the performance of the signalling this week. All the little bugs, glitches and issues which are just about masked when everything is running normally in the current not-overly-intensive timetable were very clearly exposed for all to see. Maybe it’s just as well LU appears to have changed its mind about the extra trains, as the signalling looks unlikely to be capable of accommodating them! I for one would have the old signalling back any day! |
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North End
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Post by North End on Oct 21, 2017 2:51:05 GMT
So in this situation, would trains run through the affected area in restricted manual mode? A through service was restored (prior to a failed train at Tooting Broadway a few minutes ago) but with severe delays - with a plan to suspend the line between Tooting Broadway and Morden for emergency engineering works between 03:00 - 04:00 Does this mean that trains would have to run in restricted manual mode for the whole section controlled by the affected VCC? It wasn’t a VCC failure as far as I know, I believe it was the SCS which is another component of the system. Others may be able to confirm for definite. In theory you could run through in RM, but my understanding is points would have to be manually secured. It might just about have been possible to secure up Morden and reverse via the depot, but in reality the level of service this could have offered would have been a non starter. The hope would have been for a quick fix, but in the event this didn’t happen. If you secure everything at Morden then this would delay resumption to normal. It’s also necessary to consider how with points manually secured each train would be authorised to move - the TBTC Rule Book isn’t really written for this to happen except as a means of getting stalled trains into platforms. Normally remote securing would be used, for which there is a full procedure laid down. You can’t just put an operating official or supervisor at the signal like in the old days, not that there would be sufficient staff immediately available now anyway. |
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Post by philthetube on Oct 21, 2017 12:34:29 GMT
The problem with reversing at Kennington is that there would be nowhere for the passengers to go, all trains running through would be full on arrival and so the station would soon become overcrowded, and is probably less able to cope than central London stations.
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Post by antharro on Oct 21, 2017 22:45:53 GMT
philthetube That's pretty much what North End was saying. Also as North End said, running an empty train down there to clear the platforms would be a good idea, but given the circumstances, somewhat impractical - there'd be a big enough backlog of trains in the area already. Sounds like the staff did the best they could under the circumstances. Personally I don't care for the Northern Line's ATO; it's always felt a bit rough to me. I find any of the other ATO lines to give a much smoother ride. Regardless, glad I was out of London a day earlier than usual this weekend!
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Post by memorex on Nov 2, 2017 14:39:25 GMT
even if that means overriding the automated train scheduling software that works out the optimum service pattern during disruption xD Sorry, I’ve only just seen this thread, but no such thing exists! The system runs trains to their booked working and won’t ‘work out the optimum service pattern’ (as much as we’d all love it to...), it’s down to the signallers and controllers to modify the trip a train is assigned to, or it’d Continue to try to route a train through a failure and stack every train up behind it!! |
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Post by goldenarrow on Nov 2, 2017 15:46:55 GMT
even if that means overriding the automated train scheduling software that works out the optimum service pattern during disruption xD Sorry, I’ve only just seen this thread, but no such thing exists! The system runs trains to their booked working and won’t ‘work out the optimum service pattern’ (as much as we’d all love it to...), it’s down to the signallers and controllers to modify the trip a train is assigned to, or it’d Continue to try to route a train through a failure and stack every train up behind it!! So even if Thales offer such a system which they do because it's in one of their training facilities, LU didn't purchase it? |
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Post by MoreToJack on Nov 2, 2017 16:23:56 GMT
If only things were that simple.
Seltrac as a whole is designed for simple, end-to-end, driverless metros. What happens when you end up with all the drivers at the wrong ends of the line for their breaks/reliefs because it's just kept running?
As much as it might have some limited application, automation is not the be all and end all, and nor should it be. Running an effective service during disruption is an art form, and long may it remain that way. We don't need further deskilling.
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cso
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Post by cso on Nov 2, 2017 17:09:32 GMT
As much as it might have some limited application, automation is not the be all and end all, and nor should it be. Try telling that to my bosses... Running an effective service during disruption is an art form, and long may it remain that way. We don't need further deskilling. Personally, for all I'm a programmer and all that... I'd much rather there was still a human involved! |
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Post by scheduler on Nov 3, 2017 19:09:30 GMT
The fact is that programmers THINK they can program a computer to solve any puzzle, and possibly they could, the problem is that the solution would be different in every case. The same sort of issue applies with creating the working timetable too. To every problem, whether it be a service disruption or confliction when writing a timetable there are multiple solutions. And the correct answer to the same issue will be different depending on other factors, such as time of day, duty rostas, etc. So catering to all of these would be like trying to program a computer to play chess when it can only see half the board. That is the timetable is loaded in the computer but the duty schedule is not.
To put it another way computers work very well with hard and fast rules, humans work better with guidelines and frameworks, or bendy rules of you like. Service recovery (and also resolving conflictions when writing a timetable) is all about applying bendy rules and computers are rubbish at those and they are incredibly difficult to program.
I would also add that IF, and it is a big IF, you didn't have staff on trains and the train completely drove itself, and you therefore didn't care where the train ended up and when the problem would be massively simplified and probably could just about be solved / programmed by a computer.
<<superteacher - posts merged to avoid double post.>>
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vato
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Post by vato on Nov 6, 2017 11:14:16 GMT
Yes. If you can remove constraints, the problem gets significantly simpler. However, it may not be simple enough even then.
This is the type of problem that often gets suggested for machine-learning. The gotcha is that there are still humans in the loop (e.g. passengers). You'd also end up with a learnt algorithm that might work well most of the time, but you would have no idea how it actually works, so tweaking is very hard.
I think there is still a place for experienced staff with the right set of tools to help them achieve this.
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