Oxonhutch
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« Reply #120 on: August 30, 2017, 15:23:00 » |
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To those of us who have undertaken risk assessments, it is always about one's position in the matrix bounded by likelihood - on the one hand - and consequences on the other, and what mitigation you employ in each part of that risk space. To my eyes, the barrier train did exactly what it was supposed to do in these circumstance. It looks to me like it was the blunt, but all powerful, back-stop against a risk that was very unlikely, but with huge negative consequences if it happened.
I will be interested to see the RIAB look into the risk assessment programme.
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Electric train
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« Reply #121 on: August 30, 2017, 15:57:48 » |
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To those of us who have undertaken risk assessments, it is always about one's position in the matrix bounded by likelihood - on the one hand - and consequences on the other, and what mitigation you employ in each part of that risk space. To my eyes, the barrier train did exactly what it was supposed to do in these circumstance. It looks to me like it was the blunt, but all powerful, back-stop against a risk that was very unlikely, but with huge negative consequences if it happened.
I will be interested to see the RIAB look into the risk assessment programme.
Although the barrier train was more likely to prevent construction site RRV▸ incursion onto the operational railway than operational rail vehicles incursion into the construction site. Having been in many rolls which have involved signing off on work similar to this the report will be interesting to read to see if it was process or human failure or a combination of the two,
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Starship just experienced what we call a rapid unscheduled disassembly, or a RUD, during ascent,”
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Oxonhutch
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« Reply #122 on: August 30, 2017, 16:10:45 » |
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Although the barrier train was more likely to prevent construction site RRV▸ incursion onto the operational railway than operational rail vehicles incursion into the construction site.
I agree you that an RRV excursion was always more likely, or a trolley for that matter.
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paul7575
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« Reply #123 on: August 30, 2017, 17:34:35 » |
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Yes, I heard that on the news this morning. However, having run through the arrivals into Waterloo up to 9:00 I can only see one that's over 10 minutes late, and that was less than 20 minutes lost around Raynes Park. So was there a problem with the signals - or someone in BBC» local news having a problem with telling today's reports from yesterday's?
IIRC▸ the opentraintimes live map showed P1 blocked for a fairly short time. The BBC tend to report these things as though the world is about to end, and then leave the story 'live' all day... Probably the usual sort of teething troubles. Paul
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eightf48544
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« Reply #124 on: August 30, 2017, 18:07:47 » |
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From RAIB▸ today (30th) 10h01
The collision occurred because a set of points were misaligned and directed the passenger train away from its intended route. The misalignment was a consequence of a temporary modification to the points control system which also caused the train driver and signaller to receive indications that the points were correctly aligned.
I would also have expected the point in question to be clipped and padlocked as well as relying on "A temporary modification to the points control system". Might burn the point motor out!
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« Last Edit: August 30, 2017, 18:20:54 by eightf48544 »
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paul7575
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« Reply #125 on: August 30, 2017, 20:27:57 » |
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I would also have expected the point in question to be clipped and padlocked as well as relying on "A temporary modification to the points control system". Might burn the point motor out!
It is a double slip crossover, with four routes/positions. IIRC▸ from other discussions there are four separate points machines, and four possible positions of the crossover. AIUI▸ they cannot be partially clipped out of use because of the way the moving blades have to interact. Clipping it in one position, say UMR to P12/13, would have taken P11 out of use. (or vice versa.) Paul
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stuving
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« Reply #126 on: August 30, 2017, 20:47:23 » |
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I would also have expected the point in question to be clipped and padlocked as well as relying on "A temporary modification to the points control system". Might burn the point motor out!
It is a double slip crossover, with four routes/positions. IIRC▸ from other discussions there are four separate points machines, and four possible positions of the crossover. AIUI▸ they cannot be partially clipped out of use because of the way the moving blades have to interact. Clipping it in one position, say UMR to P12/13, would have taken P11 out of use. (or vice versa.) Paul That doesn't sound quite right. Surely the four routes only occur in two pairs, i.e. it has just two positions. If all the movements are linked, however many motors do the pushing, then you can't lock out one route without blocking the other route linked to it. If they all moved independently that might not be true - though detection might be an issue.
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SandTEngineer
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« Reply #127 on: August 30, 2017, 21:34:27 » |
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I would also have expected the point in question to be clipped and padlocked as well as relying on "A temporary modification to the points control system". Might burn the point motor out!
It is a double slip crossover, with four routes/positions. IIRC▸ from other discussions there are four separate points machines, and four possible positions of the crossover. AIUI▸ they cannot be partially clipped out of use because of the way the moving blades have to interact. Clipping it in one position, say UMR to P12/13, would have taken P11 out of use. (or vice versa.) Paul That doesn't sound quite right. Surely the four routes only occur in two pairs, i.e. it has just two positions. If all the movements are linked, however many motors do the pushing, then you can't lock out one route without blocking the other route linked to it. If they all moved independently that might not be true - though detection might be an issue. The point end approached by the passenger train that was incorrectly set is operated as a double slip pair. The third end, controlled by the same point identity, was under the barrier train. On a double slip each end is a pair that operate together from a single point operating mechanism. I'll post up a drawing later. In the meantime here is a video that shows the principle of operation. Its not in the UK▸ but the principles are the same: https://youtu.be/VpfJdm71u6g
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« Last Edit: August 30, 2017, 21:43:23 by SandTEngineer »
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stuving
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« Reply #128 on: August 30, 2017, 22:29:05 » |
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The point end approached by the passenger train that was incorrectly set is operated as a double slip pair. The third end, controlled by the same point identity, was under the barrier train. On a double slip each end is a pair that operate together from a single point operating mechanism. I'll post up a drawing later.
Ah - so it is linkage (mechanical or not), but not what I said. After all, even if two routes can be set through that crossing at once, only one can be signalled - so there's no need to bother about their compatibility. It's more like linking the two ends of a crossover, and extending that to a third point end that can't usefully be moved independently. And then trying to quickly alter it temporarily.
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stuving
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« Reply #129 on: August 30, 2017, 22:52:12 » |
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BBC» South Today just now were reporting that the low-numbered platforms (not sure how many) will close again tonight, for more fixing. There was talk about people being unaware of their last train being cancelled. This is on SWR» 's site, though not in all the obvious places: Alterations to services due to additional late night engineering works at London Waterloo
We have been advised that access is required at London Waterloo station from 22:45 to work on signalling equipment, this access will limit the number of platforms trains can use.
Seven trains will be altered this evening and advertised trains may leave London Waterloo from different platforms.
The following services have been amended:
· 21:33 London Waterloo via Twickenham train will terminate at Raynes Park · 21:46 Guildford to London Waterloo train will terminate at Wimbledon · 22:07 Guildford to London Waterloo train will terminate at Wimbledon · 22:57 London Waterloo via Twickenham train will start at Raynes Park · 22:15 Alton to London Waterloo train will terminate at Surbiton · 23:03 London Waterloo to Guildford train will start at Wimbledon · 23:48 London Waterloo to Basingstoke train will start at Surbiton
If you are travelling from London Waterloo station later tonight, you are advised to check your journey before travelling.
If you have advanced booked tickets for these trains, you will be able to travel on alternative trains. So that looks like a case of having to take an alternative train and change - the question is whether in any cases the Waterloo departure is earlier.
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stuving
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« Reply #130 on: August 31, 2017, 21:27:07 » |
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Back to normal ... and today's normal is: Incident created 31/08/2017 18:49 Last updated 31/08/2017 19:31 Route affected Between London Waterloo and Portsmouth Harbour / Alton / Guildford / Epsom / Woking / Reading / Weymouth / Poole TOC▸ (s) affected South Western Railway; Description Following a track circuit failure at London Waterloo all lines have now reopened. What's Going On: Train services running to and from this station may be delayed by up to 20 minutes. Disruption is expected until 21:00. What South Western Railway Are Doing About It: The signalling problem at London Waterloo has been temporarily fixed to allow trains to run on all lines. Engineers will be applying a permanent fix later today. South Western Railway may need to alter some trains but it will now have a minimal affect on the wider service. The Twitter timeline shows that it only took 10 minutes from problem to all lines open, or rather it looks like platform 8 is not being used. Much the same happened earlier and took longer and led to a couple of trains being part cancelled. There were also cancellations announced by SWR» to SE services, which sounds odd. They are borrowing a platform (21, currently) for a week, accessed via the Nine Elms Flyover, or in other words by playing at being Eurostars.
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paul7575
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« Reply #131 on: September 01, 2017, 13:25:54 » |
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There were also cancellations announced by SWR» to SE services, which sounds odd. They are borrowing a platform (21, currently) for a week, accessed via the Nine Elms Flyover, or in other words by playing at being Eurostars.
P21 and P22 was planned for SE. I think what has been happening is that if disruption to the wider SWR service is forecast, then they are being pre-emptively diverted to Blackfriars. Lose access to a main line (whether DMF, UMF, UMR) in the station throat and the knock on effects ripple across the other 5 lines. The fact that Blackfriars appears to have spare capacity to take that 2 tph service anyway is intriguing, it is as if the four days planned at Waterloo was only being done to create a precedent for future use? There seems to be a greater emphasis on normal "run of the mill" random faults at the moment. AIUI▸ no recent modifications were made to the platform lines on the Windsor side and in the middle of the array of platforms used by main fast trains. It stands to reason that there will be a minor fault every few days or weeks, it has always been so. Paul
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Electric train
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« Reply #132 on: September 01, 2017, 22:32:43 » |
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There were also cancellations announced by SWR» to SE services, which sounds odd. They are borrowing a platform (21, currently) for a week, accessed via the Nine Elms Flyover, or in other words by playing at being Eurostars.
P21 and P22 was planned for SE. I think what has been happening is that if disruption to the wider SWR service is forecast, then they are being pre-emptively diverted to Blackfriars. Lose access to a main line (whether DMF, UMF, UMR) in the station throat and the knock on effects ripple across the other 5 lines. The fact that Blackfriars appears to have spare capacity to take that 2 tph service anyway is intriguing, it is as if the four days planned at Waterloo was only being done to create a precedent for future use? There seems to be a greater emphasis on normal "run of the mill" random faults at the moment. AIUI▸ no recent modifications were made to the platform lines on the Windsor side and in the middle of the array of platforms used by main fast trains. It stands to reason that there will be a minor fault every few days or weeks, it has always been so. Paul There are no long term plans to run SE Trains into Waterloo, once this Christmas is over he temporary electrification infrastructure put in place to enable the use of lindford St curve gets removed; indeed there is no capacity at Waterloo for SE Trains. The reason it was decided to run SE Trains into Waterloo was for the benefit of passengers from Kent that normally use Waterloo East and Charing Cross. There is no added capacity at Blackfriars currently a number of services are not running into Blackfriars during the London Bridge rebuild, the same as Thameslink services are not running via London Bridge, in fact the TLP trains via Loughborough Jcn and Herne Hill are taking the paths of the Blackfriars terminators, in the 2018 full opening of London Bridge there will be reinstatement of Blackfriars terminators.
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Starship just experienced what we call a rapid unscheduled disassembly, or a RUD, during ascent,”
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paul7575
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« Reply #133 on: September 02, 2017, 12:14:30 » |
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The point end approached by the passenger train that was incorrectly set is operated as a double slip pair. The third end, controlled by the same point identity, was under the barrier train. On a double slip each end is a pair that operate together from a single point operating mechanism. I'll post up a drawing later. In the meantime here is a video that shows the principle of operation. Its not in the UK▸ but the principles are the same: https://youtu.be/VpfJdm71u6gDid you manage to find a drawing? I'm thinking the signalling panel engraved lines means something the way they are drawn, presumably they show the default straight route (i.e. P11 left <> DMR right) with everything set normal? I had a quick glance at the hardware from a passing train and it looks like these are "clamp lock" operation, does that affect how the pairs are linked/operated? Paul
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SandTEngineer
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« Reply #134 on: September 06, 2017, 16:37:03 » |
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The point end approached by the passenger train that was incorrectly set is operated as a double slip pair. The third end, controlled by the same point identity, was under the barrier train. On a double slip each end is a pair that operate together from a single point operating mechanism. I'll post up a drawing later. In the meantime here is a video that shows the principle of operation. Its not in the UK▸ but the principles are the same: https://youtu.be/VpfJdm71u6gDid you manage to find a drawing? I'm thinking the signalling panel engraved lines means something the way they are drawn, presumably they show the default straight route (i.e. P11 left <> DMR right) with everything set normal? I had a quick glance at the hardware from a passing train and it looks like these are "clamp lock" operation, does that affect how the pairs are linked/operated? Paul Paul, still trying to find my drawings. Might have to sketch it out myself......but have found a basic animation here: http://www.dccwiki.com/images/2/2f/CrossingDoubleSlip.gif You are correct about the panel presentation and the fact the points concerned are Clamplock operated.
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« Last Edit: September 06, 2017, 16:45:17 by SandTEngineer »
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