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Post by compsci on Nov 30, 2018 8:40:57 GMT
It's worth saying (I think that this has been alluded to, but not said explicitly) that any form of additional lock on the J door will be a safety-critical system and will need to be designed and tested to similar standards to signalling.
Magnetic locking systems can and do fail closed even when they are supposed to fail open owing to faults in the control system, and so in a building access situation an emergency break glass that is wired in series with the power to the electromagnet is provided on the secure side of the door. In many cases there will also be a relay in the same circuit connected to the fire alarm so that the door unlocks when the fire alarm sounds. Both of these emergency overrides are "dumb" in that there are no complex electronics involved and so it is easy to prove that they will operate as expected, subject to the operation of a small number of components that can be designed and tested to high standards of certainty. If power was supplied only via traction current rather than any batteries then this principle would be followed, but as soon as any extra overrides e.g. door stays locked for N minutes after loss of power are added then something which could fail in the wrong direction has been added to a critical system.
There was a case a few years ago in a university building that I worked in where one of the two maglock control systems in the building malfunctioned and essentially locked itself inside a room that it was responsible for securing. It was possible to cut the power at the main distribution board but it had a battery backup that would have lasted for several days. As it was on the same circuit as the projectors in the main lecture theatre this would have meant no lectures for a few days and so instead the thinnest member of staff crawled into the room through a vent shaft. There is now an appropriate means of bypassing the maglock system if it is unhappy.
Perhaps the best solution would be to use an additional locking system that doesn't lock the door but instead locks a flap covering the existing external handle. That way the driver is able to open the door in an emergency using just the door handle, exactly as they currently do and even if the new lock disengages (e.g. if the train is gapped) then the door will stay closed even though the external handle will no longer be completely secured.
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class411
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Post by class411 on Nov 30, 2018 10:13:39 GMT
It's worth saying (I think that this has been alluded to, but not said explicitly) that any form of additional lock on the J door will be a safety-critical system and will need to be designed and tested to similar standards to signalling. Magnetic locking systems can and do fail closed even when they are supposed to fail open owing to faults in the control system, and so in a building access situation an emergency break glass that is wired in series with the power to the electromagnet is provided on the secure side of the door. In many cases there will also be a relay in the same circuit connected to the fire alarm so that the door unlocks when the fire alarm sounds. Both of these emergency overrides are "dumb" in that there are no complex electronics involved and so it is easy to prove that they will operate as expected, subject to the operation of a small number of components that can be designed and tested to high standards of certainty. If power was supplied only via traction current rather than any batteries then this principle would be followed, but as soon as any extra overrides e.g. door stays locked for N minutes after loss of power are added then something which could fail in the wrong direction has been added to a critical system. There was a case a few years ago in a university building that I worked in where one of the two maglock control systems in the building malfunctioned and essentially locked itself inside a room that it was responsible for securing. It was possible to cut the power at the main distribution board but it had a battery backup that would have lasted for several days. As it was on the same circuit as the projectors in the main lecture theatre this would have meant no lectures for a few days and so instead the thinnest member of staff crawled into the room through a vent shaft. There is now an appropriate means of bypassing the maglock system if it is unhappy. Perhaps the best solution would be to use an additional locking system that doesn't lock the door but instead locks a flap covering the existing external handle. That way the driver is able to open the door in an emergency using just the door handle, exactly as they currently do and even if the new lock disengages (e.g. if the train is gapped) then the door will stay closed even though the external handle will no longer be completely secured. This just shows that TPTB (The Powers That Be) are between a rock and a hard place. If you (i.e. rules and regs) insist that there must be a fail safe system that has to enable passengers to access the driving cab in the event of an unresponsive driver, then it's going to be difficult, complicated, and expensive. However, let's do a sanity check here. Has there ever, in the history of the underground, been a situation where passengers needed to access the driving cab, for a safety critical reason, and the driver was not capable of granting admittance? |
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Post by trt on Nov 30, 2018 11:45:17 GMT
Be a slight digression here, but the frequency of these kinds of things is often overlooked. It really gets to me that the standard procedure for putting VIPs (Visually Impaired Person) on a tube appears to be stick them in the compartment nearest the driver just in case, even though there are several stations on the network where the front doors don't open, so in order to get off the VIP has to be guided down the gangway to the second set of doors. I can say there's a chance of 1 that the VIP will get off the tube as part of their journey, and a chance of 1 in 20,000 (less probably) that the driver will need to come out of their cab to take care of them. As a passenger, I've seen the VIP get to Moorgate on the SB northern and have to be guided to the second set of doors squeezing through a crowded gangway- it's ridiculous.
So it needs to be born in mind that we have had more instances of passengers gaining entry to the driving cab without good cause than with. I guess you need to multiply that by the possible severity...
---EDIT---
Added the missing expansion of the abbreviation. Oops. Sorry about that!
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Post by greggygreggygreg on Nov 30, 2018 12:17:15 GMT
Wouldn't a VIP have some sort of escort with them? I would be surprised if a VIP that was that important would be using the Underground? Or should you be posting the arrangements for VIPs on here for security reasons?
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Post by superteacher on Nov 30, 2018 12:44:32 GMT
Wouldn't a VIP have some sort of escort with them? I would be surprised if a VIP that was that important would be using the Underground? Or should you be posting the arrangements for VIPs on here for security reasons? In this context, VIP stands for Visually Impaired Person / Passenger. |
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Post by whistlekiller2000 on Nov 30, 2018 12:54:17 GMT
Wouldn't a VIP have some sort of escort with them? I would be surprised if a VIP that was that important would be using the Underground? Or should you be posting the arrangements for VIPs on here for security reasons? In this context, VIP stands for Visually Impaired Person / Passenger. |
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Post by compsci on Nov 30, 2018 13:39:13 GMT
Has there ever, in the history of the underground, been a situation where passengers needed to access the driving cab, for a safety critical reason, and the driver was not capable of granting admittance? Perhaps the right question to ask is whether there has ever been a need for a passenger to access a driving cab for safety critical reasons on any railway, since we could be considering a low frequency, high severity incident. After thinking a bit more, I think that any incident that only involved a driver being incapacitated is a red herring, as if this were a concern then there would be emergency releases on the cab to saloon doors of National Rail trains. But there aren't, so that only leaves trains where the only means of emergency egress is via an end door, which in the case of LU trains at least is accessed via the cab. NR class 313 and 717 trains also have end doors for evacuation owing to the size of the tunnels between Drayton Park and Moorgate. So it would be interesting to consider if either of these trains have either passenger-operated emergency releases on the cab to saloon door or some other means of passengers self-evacuating via the end doors e.g. the inactive cab being closed off like the gangways between coupled units. If they don't then this leads to a conclusion that this is either totally unsafe (unlikely as they have been approved to operate) or else that there is no need for passengers to be able to self-evacuate via a cab. |
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Post by trt on Nov 30, 2018 13:57:16 GMT
Are there not break glass panels on the door releases of NR trains? I hadn't specifically looked, just always assumed they were there. I think the instance of drivers being incapacitated and needing emergency assistance probably outnumbers evacuations through the end doors; heart attacks and all that - read about it from time to time with bus drivers and stuff.
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class411
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Post by class411 on Nov 30, 2018 14:10:47 GMT
Has there ever, in the history of the underground, been a situation where passengers needed to access the driving cab, for a safety critical reason, and the driver was not capable of granting admittance? Perhaps the right question to ask is whether there has ever been a need for a passenger to access a driving cab for safety critical reasons on any railway, since we could be considering a low frequency, high severity incident. Well, I did think of saying 'any railway, anywhere, ever'. I suspect that the answer is still: 0. |
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Post by norbitonflyer on Nov 30, 2018 14:19:45 GMT
NR class 313 and 717 trains also have end doors for evacuation owing to the size of the tunnels between Drayton Park and Moorgate. Other examples exist, such as Class 319 (for the now-closed tunnels near Barbican) and the 378s (for the Thames Tunnel). I assume that they are also needed on the Liverpool Loop, as the 503s were fitted with them when that line opened in the 1970s, despite their relatively short life expectancy (already nearly 40 years old when the Loop opened). They were replaced eight years later by the 507s and 508s, which are DC only versions of the 313s, and have end doors, as will their replacements, class 777. Although the 314s built for the "Argyle Line" tunnel services in Glasgow are similar to the 313s and also have end doors, they have always shared the work with other classes without end doors (303, 318, 320, 334). Indeed, the class 318s had their end gangways removed when relegated to local services through the tunnels). (I don't think gangway-fitted 380s and 385s generally work the cross-Glasgow tunnel services) |
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Post by compsci on Nov 30, 2018 15:27:47 GMT
I've come across a RSSB standard which says that: This makes it clear that it is expected that passengers are able to evacuate themselves from either end of the train, so anything that required intervention from the driver wouldn't be acceptable. However (and this is a big caveat) I doubt that this standard was written with the risk to drivers of passengers being able to access cabs in mind. So any modifications will need to respect the standard until it can be reviewed and changed as needed. All this assumes that RSSB standards apply to LU, which might not be the case. However they definitely apply to NR class 378, which has a break glass and class 718, which has a cab which can be changed into a gangway to allow access to the end door. But does it have a break glass to allow access to the cab which is in use? |
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Post by norbitonflyer on Nov 30, 2018 15:39:13 GMT
I doubt that this standard was written with the risk to drivers of passengers being able to access cabs in mind. ? Really?
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Post by compsci on Nov 30, 2018 16:05:19 GMT
The first time I read 7.3.3, I interpreted it as "interference with driver controls" and "interference with vehicle controls", though on a second reading it does look more like "interference with the driver" (the person) and "interference with vehicle controls".
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Post by commuter on Dec 3, 2018 13:44:42 GMT
I've come across a RSSB standard which says that: This makes it clear that it is expected that passengers are able to evacuate themselves from either end of the train, so anything that required intervention from the driver wouldn't be acceptable. However (and this is a big caveat) I doubt that this standard was written with the risk to drivers of passengers being able to access cabs in mind. So any modifications will need to respect the standard until it can be reviewed and changed as needed. All this assumes that RSSB standards apply to LU, which might not be the case. However they definitely apply to NR class 378, which has a break glass and class 718, which has a cab which can be changed into a gangway to allow access to the end door. But does it have a break glass to allow access to the cab which is in use? Railway Group Standards do not apply to L.U.L, who have their own Standards. There is however an internal process to either reconcile Railway Group standards for inter working on the main-line railway system where Network Rail has responsibilities, or agree some form of non-compliance. L.U.L has its own standard, S1180 which specifies that access and egress from the front and rear from car to track and vv must be supplied. |
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Post by norbitonflyer on Dec 3, 2018 15:10:15 GMT
There is however an internal process to either reconcile Railway Group standards for inter working on the main-line railway system where Network Rail has responsibilities, or agree some form of non-compliance. . There is only one pair of single track tunnels (at Kensal Green) on the sections of NR on which LUL trains run. Given that the class 710s that will soon be using those tunnels on a regular basis have no end doors, I doubt that, to quote the RSSB standard, it is a place "where it has been deemed necessary that passenger vehicles require train end egress facilities (see 7.1.1 of this document)". |
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Post by Dstock7080 on Dec 3, 2018 15:17:57 GMT
As there are no single track tunnels, (or indeed any tunnels at all) on either of the sections of NR on which LUL trains run I doubt that it has been "deemed necessary" that egress is required. Kensal Green ? |
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Post by up1989 on Dec 3, 2018 22:53:47 GMT
Thing is the tunnel at kensal green is wide enough for people to evacuate the train via the usual doors, so the 710 doesn't need the end doors. I think the 710s won't be allowed to work the east london line tho, due to the thames tunnel.
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Post by Dstock7080 on Nov 21, 2019 15:31:33 GMT
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rincew1nd
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Post by rincew1nd on Nov 21, 2019 16:16:33 GMT
"How does it erm, how does it work?"
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Chris M
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Post by Chris M on Nov 21, 2019 16:29:38 GMT
"How does it erm, how does it work?" From the label on the left of the photo: - Lift flap and press button
- Button will flash for X [sic] minutes
- When button illuminates continuously, lift cover and turn door handle
That needs some serious rewording though: - The difference between "flap" and "cover" is not obvious
- "X minutes" is really unhelpful
- there is no indication which way to turn the door handle - not that it looks like a door handle, and nor does it look easy to turn as there appears to be no way to grasp it
- There is no indication of a reason what to do if the button stops flashing, or why it might do that (I'm assuming that as purpose of this exercise is to allow t/ops to deny entry when it isn't required that there is some way for them to do this and that, if this happens, the button will stop flashing.
- There is no apparent mention of the existing emergency stop plungers or that this is (presumably) the best way to communicate with the driver if needed
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Post by brigham on Nov 21, 2019 16:53:45 GMT
This is to satisfy union requirements, whilst also complying with the emergency escape regs.
Whether the passengers can work out how to use it is low on the list of priorities.
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Post by underover on Nov 21, 2019 18:04:27 GMT
"How does it erm, how does it work?" From the label on the left of the photo: - Lift flap and press button
- Button will flash for X [sic] minutes
- When button illuminates continuously, lift cover and turn door handle
That needs some serious rewording though: - The difference between "flap" and "cover" is not obvious
- "X minutes" is really unhelpful
- there is no indication which way to turn the door handle - not that it looks like a door handle, and nor does it look easy to turn as there appears to be no way to grasp it
- There is no indication of a reason what to do if the button stops flashing, or why it might do that (I'm assuming that as purpose of this exercise is to allow t/ops to deny entry when it isn't required that there is some way for them to do this and that, if this happens, the button will stop flashing.
- There is no apparent mention of the existing emergency stop plungers or that this is (presumably) the best way to communicate with the driver if needed
X numbers of minutes to me makes it sound like this is a mock up which was then shown to union reps. Then a discussion could be had on how long the timer should be set at etc? It would be interesting to see just how strong that electro-magnet is. I wonder if you could pry it open with a key? |
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Post by superteacher on Nov 21, 2019 19:14:35 GMT
X minutes - love a bit of algebra!
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Post by phoenixcronin on Nov 21, 2019 20:54:57 GMT
Where does the normal J key go? Is it hidden under the flap with the orange ring? Maybe I'm missing something but I can't see it. It can't be the silver/metal circular thing on the left as a J key barrel would need to have a square "element" on the inside.
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Post by MoreToJack on Nov 21, 2019 20:59:44 GMT
This replaces access via a traditional J-door key.
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Post by phoenixcronin on Nov 21, 2019 21:02:01 GMT
Ah right, I see. I thought this was just a way of preventing unauthorised access to the handle. Didn't realise the keys are changing as well.
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Post by philthetube on Nov 22, 2019 9:23:30 GMT
Is there an instant open option for drivers to use when changing ends, also will it be secure when the train is shut down.
Will it be possible to open this to gain access to the rear cab when the train is opened up at the other end?
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Post by tjw on Nov 22, 2019 11:40:10 GMT
Is there an instant open option for drivers to use when changing ends, also will it be secure when the train is shut down. Will it be possible to open this to gain access to the rear cab when the train is opened up at the other end? I think I see a key and lock, I am sure each driver (and anyone else who feels they need a key) will be given new keys to open said door immediately, without delay. Adding new locks is nothing new on the Railways... Originally we had a Carriage key that opened most doors, (Restaurant cars i.e. GNR (Great Northern Railway) for instance had a pad lock key and special door key). Because everyone had the carriage key we gained the Mk1 key to further control access, until everyone had the Mk 1 key! Then we saw padlocks being added to the catering vehicles kitchen and pantry doors and flaps. As for the readability of the instructions... If you can't follow those instructions, it may not be safe for you to enter said door! |
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Post by PiccNT on Nov 22, 2019 14:18:09 GMT
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rincew1nd
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Post by rincew1nd on Nov 22, 2019 20:50:33 GMT
This video probably answers most people's questions about the new system. Admin commentPlease include some context rather than just linking to sites away from the forum. |
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