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Post by roman80 on Feb 10, 2020 21:40:27 GMT
I saw an interesting occurrence at London Bridge at about 610pm this evening. The westbound train I was on started to depart London Bridge but after moving about a carriage length the emergency stop cut in. A number of folks near me lost their balance. The driver immediately announced a PED door had opened as the train was leaving, causing the emergency brake activation. After a delay of a few minutes the driver announced the platform staff had dealt with the door in question and we departed.
How does the train find this out so quickly? Is there a point of no return once a train has started to move after which such an indication is ignored?
This is the first time I've seen this type of occurrence since the extension opened.
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Post by goldenarrow on Feb 10, 2020 22:27:54 GMT
I'm just guessing here but the same technology that is used to coordinate between the train and platform edge doors opening would be surely be able to stop a train within the countdown markers when detecting the loss of a Doors Closed Visual.
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Post by brigham on Feb 11, 2020 8:36:56 GMT
Another disadvantage of Platform Edge Doors; If one stays open, it brings trains to a standstill.
Do we really need this?
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Post by punkman on Feb 11, 2020 10:42:19 GMT
Under ATO the platform edge door system is linked in so that a train can't move if one or more of the platform doors aren't closed, in a similar way to the pilot light (door closed visual) on the trains themselves. In the case you witnessed yesterday a PED would have somehow opened (even by a tiny amount e.g. by someone leaning on it) or more likely just an indication that it had i.e. an electrical malfunction. This has the effect of shutting down the area (technical term - "closing the track") within the platform so that any trains there or immediately approaching will be emergency braked while those further away will be brought to a smooth standstill until the fault can be rectified. (I'm not sure of the exact range.) This is done by station staff having to isolate that door from the rest to allow the system to restore ("opening the track").
It is a safety feature that a PED should not be open when a train is not properly berthed as, for example, a partially sighted person might assume there WAS a train there if one was open. My understanding of how things worked pre ATO was that it was up to the driver to stop the train if a door opened, having seen a platform door light come on in his or her on-board monitors. It seems now that this sort of thing is becoming more common, with several instances of isolated doors at any one time across the 8 PED stations. I guess at 20 years old things are not as reliable! On the whole PEDs are a good idea, but it does seem a waste of resources every time one fails that a member of station staff has to supervise that door at all times.
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Chris M
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Post by Chris M on Feb 11, 2020 12:16:48 GMT
Another disadvantage of Platform Edge Doors; If one stays open, it brings trains to a standstill. Do we really need this? Given the rarity of delays caused by PED failures compared to delays caused by things PEDs prevent (e.g. people and objects on the track) and that PED-related incidents are almost always less serious than people on the track (and some objects on the track), plus the primary airflow management benefits of PEDs, on balance they are a significant net positive. |
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Post by roman80 on Feb 11, 2020 14:37:29 GMT
Under ATO the platform edge door system is linked in so that a train can't move if one or more of the platform doors aren't closed, in a similar way to the pilot light (door closed visual) on the trains themselves. In the case you witnessed yesterday a PED would have somehow opened (even by a tiny amount e.g. by someone leaning on it) or more likely just an indication that it had i.e. an electrical malfunction. This has the effect of shutting down the area (technical term - "closing the track") within the platform so that any trains there or immediately approaching will be emergency braked while those further away will be brought to a smooth standstill until the fault can be rectified. (I'm not sure of the exact range.) This is done by station staff having to isolate that door from the rest to allow the system to restore ("opening the track"). It is a safety feature that a PED should not be open when a train is not properly berthed as, for example, a partially sighted person might assume there WAS a train there if one was open. My understanding of how things worked pre ATO was that it was up to the driver to stop the train if a door opened, having seen a platform door light come on in his or her on-board monitors. It seems now that this sort of thing is becoming more common, with several instances of isolated doors at any one time across the 8 PED stations. I guess at 20 years old things are not as reliable! On the whole PEDs are a good idea, but it does seem a waste of resources every time one fails that a member of station staff has to supervise that door at all times. Thanks, very helpful. |
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jimbo
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Post by jimbo on Feb 11, 2020 23:52:30 GMT
Another disadvantage of Platform Edge Doors; If one stays open, it brings trains to a standstill. Do we really need this? Given the rarity of delays caused by PED failures compared to delays caused by things PEDs prevent (e.g. people and objects on the track) and that PED-related incidents are almost always less serious than people on the track (and some objects on the track), plus the primary airflow management benefits of PEDs, on balance they are a significant net positive. So will Battersea & nine elms see PEDs? |
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Post by goldenarrow on Feb 12, 2020 0:12:49 GMT
Given the rarity of delays caused by PED failures compared to delays caused by things PEDs prevent (e.g. people and objects on the track) and that PED-related incidents are almost always less serious than people on the track (and some objects on the track), plus the primary airflow management benefits of PEDs, on balance they are a significant net positive. So will Battersea & nine elms see PEDs? No PED provision on the NLE, there was talk of them being introduced during a Mayoral question session in early 2017 but that was before World Class Capacity was canned. Stations have been built with passive provision for PEDs should circumstances change. |
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Post by brigham on Feb 12, 2020 8:23:55 GMT
Given the rarity of delays caused by PED failures compared to delays caused by things PEDs prevent (e.g. people and objects on the track) and that PED-related incidents are almost always less serious than people on the track (and some objects on the track), plus the primary airflow management benefits of PEDs, on balance they are a significant net positive. Yes, and they would be even more of a 'net positive' if a failed one didn't automatically stop traffic. (Which is what I was trying to say in the first place). |
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