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Post by Deleted on Jul 3, 2016 23:26:48 GMT
Notes to Admin/Moderators: Please feel free to lock or amend this thread as necessary. I do not intend to look at specific incidents or discuss the driver’s liability/work practices on this thread. I merely want to discuss the technicality behind it and how it can happen. I know this has been discussed in the press but I will not attach links as I do not want to mention specific incidents.
As a frequent user of the Piccadilly Line I have noticed many times as a train pulls into a station the doors open before the train has fully come to a halt. It can be micro-seconds but it is still before the train has stopped. How can this happen? Isn’t there a system mechanically that should prevent a door opening before a train has stopped? Can anybody explain this to me?
Hope some of you can shed some light.
Best Regards
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Chris M
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Post by Chris M on Jul 3, 2016 23:43:53 GMT
On older stocks, the doors can be opened by the driver when the speed is lower than a set limit (I can't remember what the limit is though). Once the doors have started opening the driver cannot retake power until the doors have closed again. I presume it must also happen in a CDSE area but I may be wrong about that.
The idea is so that doors are fully open at moment the trains comes to a stop, so that passengers can instantly alight. This is in contrast to the modern stocks where on occasion 10-20 seconds is wasted with the train stationary and the doors closed.
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North End
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Post by North End on Jul 4, 2016 6:51:04 GMT
On older stocks, the doors can be opened by the driver when the speed is lower than a set limit (I can't remember what the limit is though). Once the doors have started opening the driver cannot retake power until the doors have closed again. I presume it must also happen in a CDSE area but I may be wrong about that. The idea is so that doors are fully open at moment the trains comes to a stop, so that passengers can instantly alight. This is in contrast to the modern stocks where on occasion 10-20 seconds is wasted with the train stationary and the doors closed. Not just older stocks, it's quite common to see doors opening just as the train comes to a stand on the 09 stock. Used to be possible on the 95 stock, although not since TBTC as the VOBC will not allow a door release until the train is proved stopped and correctly positioned - resulting in a delay of about a second before the doors can be opened. Previously it was useful to be able to open whilst coming to a stand if the driver was overrunning the mark slightly, although this would certainly get flagged up during an assessment. I've never known it be a factor in any incident however, so my personal view is the benefits of being able to open early outweigh the tiny risk.
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Post by stapler on Jul 4, 2016 7:01:15 GMT
The same must apply to NR stock. Having spent a few days riding around on now ageing class 321s, with guard operation on most, it was noticeable how slick the door light-on operation was compared with (say) LU 92TS...
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Post by brigham on Jul 4, 2016 8:12:15 GMT
It was quite common to see the doors opening well before the train had stopped; particularly at Waterloo. The amount of valuable time saved was amazing.
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Post by Deleted on Jul 4, 2016 14:25:44 GMT
If your purely going on the CSDE side of things the train can open the doors 1.6 metres from its normal stopping mark.
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Antje
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Post by Antje on Jul 4, 2016 17:12:40 GMT
It is ultra ultra common in Paris too, and in some cases passengers are able to step off to the platform before the train had fully stopped, even if only by a second or less. This is possible on most trains with user-operated doors, which currently ranges from the MP59 (1963) to relatively new MI09 (2011).
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Post by lazythread on Jul 4, 2016 19:08:16 GMT
I've recently started using LU again when visiting my Daughter in Balham and it's painful waiting for the doors to open now. It was much slicker in the past.
Having been a bus driver in the past my ritual was stop - parking brake on - hit that door open button ASAP. A bus or train stopped is not earning it's keep.
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Post by PiccNT on Jul 4, 2016 20:59:26 GMT
Yes, on the 1973 stock, it has to be within the CSDE zone and the drivers console buttons are governed by the speed sensing relay and this allows the doors to be opened I believe under 5 MPH. We are however trained to use a finger from each hand when operating the two open buttons and you therefore can't open them until the TBC is released so no doors to be opened until the train has stopped. However, in the real world ....
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Post by patrickb on Jul 4, 2016 21:05:50 GMT
Doors opening slightly prematurely was something I distinctly remember on the C Stock and 73's. Sadly the PTI in general is being vastly 'improved' in response to 'safety'. With the implementation of TBTC and PED's, especially in Central Area Station, customers won't be able to benefit from the early boarding and/or alighting.
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Post by will on Jul 4, 2016 21:13:24 GMT
I've recently started using LU again when visiting my Daughter in Balham and it's painful waiting for the doors to open now. It was much slicker in the past. Having been a bus driver in the past my ritual was stop - parking brake on - hit that door open button ASAP. A bus or train stopped is not earning it's keep. Definitely agree the 1995/6 stocks seem to take an age to open their doors. The whole TBTC ATO system seems so sluggish even with accelerating and the breaking rate is painfully slow compared to say the Victoria Line. Is it my imagination or is the Jubilee faster than the Northern ?
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North End
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Post by North End on Jul 4, 2016 21:19:13 GMT
I've recently started using LU again when visiting my Daughter in Balham and it's painful waiting for the doors to open now. It was much slicker in the past. Having been a bus driver in the past my ritual was stop - parking brake on - hit that door open button ASAP. A bus or train stopped is not earning it's keep. Definitely agree the 1995/6 stocks seem to take an age to open their doors. The whole TBTC ATO system seems so sluggish even with accelerating and the breaking rate is painfully slow compared to say the Victoria Line. Is it my imagination or is the Jubilee faster than the Northern ? Jubilee is very slow in the open sections. Did Wembley Park to Stanmore last week and even this short journey seemed to take an age - all due to minimum brake rate. Valuing time hardly.
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Post by Deleted on Jul 4, 2016 21:26:27 GMT
I've seen doors on the 09 stock open early but not as early as older stocks.
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Post by trainopd78 on Jul 10, 2016 19:09:07 GMT
Unfortunately the doors wont open until the tbtc signalling system tells the train its safe to open them. Thats generally 3 seconds. On a line like the district with 40 stations end to end that 120 secs minimum of lost time through door opening or to put it another way 2 tph lost!! Still thats progress i suppose.
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Post by will on Jul 11, 2016 9:11:18 GMT
Unfortunately the doors wont open until the tbtc signalling system tells the train its safe to open them. Thats generally 3 seconds. On a line like the district with 40 stations end to end that 120 secs minimum of lost time through door opening or to put it another way 2 tph lost!! Still thats progress i suppose. I really hope Thales get their fingers out and sort out issues like these before the SSR is signalled as we can't cope with slow door openings on the SSR as maintaining the proposed 32tph service frequency on the core sections is likely to be difficult at times due to all the junctions etc. As well as that if they provide the same substandard product they did for the Jubilee and Northern lines we'll have half the Metropolitan line going non communicating and trains crawling into stations due to the minimum braking rate that apparently must be enforced on all open sections of track regardless of conditions.
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Post by trainopd78 on Jul 11, 2016 14:12:34 GMT
Personally I cant see it happening. I know we're replacing those loops with beacons which means easier re-entering as the beacons are closer together than the loops, but apart from that ive been led to beleive that its more of the same. I cant wait until its first leaf fall season up on the Amersham road.
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Post by philthetube on Jul 11, 2016 18:19:29 GMT
off topic, but I cannot understand why ATO. North of Harrow
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Post by superteacher on Jul 11, 2016 21:49:56 GMT
<<Can we stick to the discussion about door opening please folks. There are other threads to discuss the shortcomings of ATO signalling systems.>>
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