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Post by dm1 on Sept 1, 2020 18:37:16 GMT
Of course the middle to end gap ratio will swap depending on the direction of travel if platforms are on opposite sides of the same track pair, or an island platform. And what's to say that the curve remains a constant radius along the platform length? So, each door plate extension will need to be calibrated for each platform. Does a carriage tip further depending on passenger load? So are strain gauges needed on the carriage suspension to compensate? What a load of variables to cope with. And, of course, the plate has to be in place before the doors are open: the video shows almost a second delay, which all slows down a service. The example I showed uses software that is calibrated to extend the step the right amount for each platform (there's a database of platforms and stopping points etc). Stadler stock uses another approach of just having sensors on the extending step itself that senses the platform edge and stops accordingly, or if the platform is lower. senses the platform below and extends to a length allowing a comfortable step up. Modern train software is capable of handling all those variables and more. A lot of stock does so already (e.g. suspension and braking adjustments based on passenger load/weight). There's no need to reinvent the wheel, just apply existing solutions to the tube environment. As for dwell time, yes, extending the step takes time, but in return you get faster boarding and alighting because there isn't a massive gap/step to negotiate. There might be a small increase in dwell time, but it's nowhere near as large as it would appear at first glance, and I imagine the safety advantages make it well worth it. The better door configuration of the new stock will speed up dwell times in any case. The existence of the gap at all will mean that dwell times will be longer than if it did not exist, so you might as well use the extra time to make it safer.
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Post by dm1 on Sept 1, 2020 10:53:55 GMT
When it was decided that S stock would berth beside platforms for level access, rather than overlapping in traditional style, investigations were made into fitting gap-fillers to each train doorway. This must have been based upon the number of platforms that would have required active gap fillers over the system, compared to the number of train doorways. Eventually they went for adjusting track and platforms to reduce the gaps, given worries over reliability of active gap fillers. Ten years since the S stock appeared, reliability will no doubt have improved, but there remains the problem of fitting such equipment within the restricted space beneath tube-gauge trains. Given that such steps (albeit a little shorter than would be required on the tube) have been fitted to trams, I wouldn't have thought space would be that much of an issue. That said, I'm no expert.
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Post by dm1 on Aug 31, 2020 21:27:17 GMT
I wonder whether these will have extensible floor plates, like much mainline stock, to fill the gaps. While these would constitute additional moving parts and failure points, presumably they could be as reliable as the doors, which these days seem pretty good. "Much mainline stock". Are you sure about that? At this moment the only mainline stock with extensible floor plates that are passed for passenger use are the Anglian 'Flirt' units (though AIUI there are several stations where they can't be deployed). MerseyRail is currently taking delivery of units with sliding steps and has rebuild every platform to the same standard so they can be used (even the platforms that currently have steps to access them). In the UK yes, but on the continent stock with gap fillers has become extremely widespread in recent years - maybe even standard under many circumstances. I personally think that using such train-mounted gap fillers is essential for the deep tube lines, and I think it would be a big mistake not to do so. The technology has shown itself to be very reliable, and no doubt significantly more reliable than any untested platform-mounted solution. Just turning a large gap into a small step would be a significant improvement, even without raising the platform heights to match the trains, which could be done later if desired. This is one example (also manufacteured by Siemens, I should add - for Stadler stock this is also a standard feature)
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Post by dm1 on Feb 26, 2020 8:10:34 GMT
This tweet may be of interest As an aside, I had a fluorescent tube (in a room at home) fail a few days ago - I replaced it with a LED tube in mere seconds. I had to replace the starter too, but that came with the tube. I was very surprised by the difference in the light - it was a far greater improvement than I had ever imagined possible. Presumably having done one, the rest will be a lot cheaper and faster since they know more or less how to do it now (excluding variation between trains)
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Post by dm1 on Sept 9, 2019 16:30:33 GMT
The official TfL status update claims that there is a Good Service on the Metropolitan Line.
The official Metropolitan Line twitter, with its tweet upon tweet of trains being cancelled between Wembley Park and Aldgate would suggest otherwise. Here is one example.
I guess at least that information is getting out, which I think is an improvement over the (as far as the Met line is concerned fairly meaningless) Minor Delays.
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Post by dm1 on Sept 3, 2019 10:15:20 GMT
There will obviously be less delay in getting the door enable system set up if you only need to align something rather than prove what its doing first. I think the point is that this should not be inherently true - at least not on a human scale. If the signalling system is designed with this in mind, there is no inherent reason why it cannot carry out the door enabling near instantaneously. Of course there might be some kind of compromises in the system that cause this - but the Victoria Line alone shows that this is not necessary. Objectively speaking if this proves to be a bottleneck (which on the Victoria line it definitely would have been) then I think there are perfectly legitimate questions about why the Thales system was designed in such a way that this delay occurs.
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Post by dm1 on Sept 2, 2019 9:36:59 GMT
Lack of appropriately trained drivers. The Met line seems to have been caught out in not getting their driver training delivered on time. The CBTC system itself is working perfectly well. Does that mean the faulty train being reported isn't actually a faulty train? Is that to do with drivers needing to drive manually (in restricted manual?) as part of their training, as mentioned earlier? On an unrelated note, it will be interesting to see which line is now faster between Finchley Road and Baker Street. Have speed limits there been changed at all?
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Post by dm1 on Aug 25, 2019 21:04:29 GMT
The class 33 is tripcock fitted; it was fitted ahead of a railtour on 29/04/2018 from Marylebone to Quainton Road. This weekend’s tours are a repeat of that, with an additional trip to Watford each day. flic.kr/p/25jtU8pNo trains are permitted to operate over the Metropolitan line, in traffic hours, without tripcocks fitted. The only exception to this is Chiltern class 172 units which must be buried between other units with tripcocks at both ends. Correct me if I'm wrong, but I'm sure I've seen a 172 on the met heading towards Marylebone with only a 165 at the front (so a tripcock only at one end rather than both). Aside from the fact that it can't go back the way it came, that shouldn't pose a problem should it?
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Post by dm1 on Apr 4, 2019 20:18:24 GMT
Follenfant's other big project was the Heathrow extension otherwise known as his folly. The route has surface and cut and cover sections linked to the tunnelled section by a very short bridge. All the classic construction techniques for a railway. why his 'folly?' whats 'wrong' with the Heathrow extension? My guess (please correct me if I'm wrong) would be the fact that it was built to tube gauge rather than SSR gauge (which prevents any SSR trains being sent there or any branch swaps with the District line).
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Post by dm1 on Mar 17, 2019 18:51:23 GMT
goldenarrow I've always wondered why they haven't put in the effort on the Jubilee Line to get that time down (or maybe they have but were unsuccessful?). Reducing that time from 10-15s to 1-2 (or less if you use the practice of opening doors as the train stops so that they are fully open by the time the train is stationary) would surely have a massive impact (~30% assuming a 30s dwell). Unless there are hardware reasons why that isn't possible, surely its much cheaper to pay for a few thousand hours of software development than spending millions on additional trains to improve the service frequency. I can only hope that they optimise this as much as possible on the SSR. Maybe some of the improvements made in CBTC will be transferable back to the older TBTC systems.
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Post by dm1 on Mar 17, 2019 18:13:40 GMT
with a door release time that is comparable with the Jubilee line. That would imply that there is room for improvement there? The Jubilee sometimes takes 15-20 seconds to open (especially at Baker Street in my experience).
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Post by dm1 on Mar 17, 2019 14:53:53 GMT
Are there any updates regarding the current schedule for the next SMAs, given the (presumably) successful launch today?
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Post by dm1 on Sept 12, 2018 15:02:46 GMT
There’s been a significant update to the CTBC software and given that it needs to be properly tested, the go live date for 0.5 has moved again..... New date is 17th/18th November Any details on exactly what has been updated/ what issues the update is meant to solve? In particular, is it an update that adds some kind of new functionality, or an update that is trying to make the functionaity that's already there err... function?
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Post by dm1 on Aug 15, 2018 9:56:51 GMT
Aren't some of the new gate lines on crossrail weatherproof? Would putting in barriers like that somewhere outside change the calculations/costs?
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Post by dm1 on Aug 4, 2018 21:06:01 GMT
Hmm that video inspires a light bulb moment. As stock on the Bakerloo gets older I guess the risk of wheel flats will rise for any rolling stock which lacks any form of wheel slip detection. That video suggests that you could quickly and easily implement a very cheap wheel flat detection system - assuming there are still signalling staff employed somewhere. Basically as trains shuttle back and forth along the same route it would only take providing the signallers cabin with a simple video camera feed with sound from a nearby platform which all trains are expected to transit. I suspect it would not take very long for the signalling staff to notice any train producing such a loud thump thump sound, and likewise will pretty much ignore the sound of any which don't. Sort of like most car drivers quickly get tuned to what sounds are normal. As and when a train sounds weird, presumably the signallers are ideally placed to identify the affected unit and get the maintenance staff to intervene to swap it out with another train whilst the problem is resolved. For very little investment the Bakerloo could potentially achieve very rapid pay-back through reduced track damage. If such a system was installed in a line control room, I can say that within 12 hours it would be turned off by one means or another. Signalling staff as you call them, do not need something that can interfere with their concentration in times of failures or incidents. Or perhaps an ideal application for machine learning?
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Post by dm1 on Jul 24, 2018 8:20:10 GMT
Bombardier and Hitachi launched a legal battle this morning in the High Court to prevent TfL awarding the contract to Siemens. The outcome of this dispute could also have possible implications for the procurement of rolling stock for High Speed 2. Great. More delays! Whilst frustrating, it's somewhat understandable from Hitachi/Bombardier's perspective. This contract effectively locks them out from decades of train orders (if Siemens doesn't mess up), so why wouldn't they take every avenue open to them to prevent that from happening?
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Post by dm1 on Jul 21, 2018 18:57:59 GMT
At risk of provoking ire - what is the big issue with over-carrying passengers?
As I understand it, trains don't tend to wait in the sidings for very long in any case (stepping back etc)?
If passengers do end up being over-carried, as long as it's made clear that they'll soon be taken back (for example by the driver when walking back through) to prevent panic, it shouldn't cause that many issues surely?
I've never quite understood the convention in recent years of avoiding reversing sidings because of this requirement (to check for passengers before using them). Many other countries transport systems seem to avoid this?
Am I missing something?
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Post by dm1 on Jan 29, 2018 22:36:32 GMT
Do other metros around the world not have the same problem? Is it caused because of the small bore our tunnels were built to? They very much do - and has little to do with bore size (at least inherently). The older stock on the Moscow Metro was (and is) notorious for being extremely loud, largely due to windows being open and very loud DC motors. Newer stock is air conditioned without opening windows, so is quieter, but has high pitched noise from AC motors instead, particularly noticeable when braking. The noise in stations is loud enough, but in tunnels it is even louder. Consistently at Jubilee Line at Baker Street levels of loudness. The best form of mitigation is of course stock without opening windows, accompanied by air conditioning. The tunnel size on the tube lines does not prevent the former, but does make the latter very challenging.
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Post by dm1 on Apr 19, 2017 14:01:35 GMT
As a long time lurker I finally felt it was time to post.
Can somebody explain the purpose of the blockade around Harrow on the Hill over the Easter weekend. The twitter feed suggested it was to do with pointwork and approach speeds?
On my most recent journey on Tuesday there appeared to be many orange people on the track still working (especially on the slow lines north of HotH). There also appeared to be lots of new ballast, some grey cables and some points appear to have been freshly painted white again.
What effects will it have on journeys and/or the timetable and was it in any way connected with the ATC signalling upgrades?
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