Faulty doors

[Deleted]

On departure from Clapham Common, the last set of double doors on this Northern Line train opened. The train continued moving for a while before the driver noticed and stopped in the tunnel.



What could cause this malfunction? The train op spent a long time trying to fix the problem, but the doors wouldn't budge.

[domh245]

Wow, That can't be good! Surely the Pilot light would have failed, and he wouldn't have been able to motor, or has the door just given in, but leaving the pilot lit? As for the incident, did you carry on eventually to the next stop and detrain, or did you do something else?

[railtechnician]

Interesting! I don't know but presume the end doors can be cut out on that stock as they can be on others. Again I don't know but perhaps that makes either faults and/or driver error more likely to cause end door open issues. I would've thought that even if the end doors are cut out they would remain in the pilot circuit but it would appear not.

[Deleted]

Apr 22, 2013 15:51:34 GMT domh245 said:

Wow, That can't be good! Surely the Pilot light would have failed, and he wouldn't have been able to motor, or has the door just given in, but leaving the pilot lit? As for the incident, did you carry on eventually to the next stop and detrain, or did you do something else?

Passengers in car 6 were moved to car 5. Everyone was detrained at the next stop.

As the train started moving from the platform, the doors opened (I was expecting this to automatically bring the train to a halt). After a while, the driver stopped and asked for the alarm to be pulled if any doors were open. The driver spent a while in the cab and under seats in the carriage, trying to fix the problem but the doors wouldn't close. Interestingly, after we all detrained, the button on the outside of the carriage that closes the doors didn't seem to have a problem with closing the faulty door.

[Colin]

The pilot dropping out only causes the motors to drop out - a loss of pilot light on its own won't demand a brake application..........so if a driver is coasting, they probably won't be aware straight away.

The end door cut out is for preventing a door from opening - it won't bypass the pilot light circuit!!

The driver did do the correct procedure in terms of stopping and asking for a handle to be pulled if there is a door open via the PA, but I'm rather concerned that there is no mention of a member of staff being posted in the affected carriage for the journey to the next station.

As for how it happened, well I wouldn't mind knowing the answer too!!

[rincew1nd]

It is appropriate to remind members of the rules when discussing this kind of thing:

7.3 (Serious Incidents and/or Major Events)

Serious incidents or other major events such as derailments, crashes, fires, weather, terrorist, etc (to give a few examples - this list is not exhaustive) can also prove to be a particularly difficult subject, especially in the early stages. These type of events will always lead to speculation and internal investigations. As a result the following applies on this forum:

•(7.3a) Forum staff members will confirm the facts when they have them to hand, though it may be some time time before this is possible.
•(7.3b) LU staff that are directly involved in an incident may post a brief outline if they feel it is appropriate - however as with our one under rule above, details of a fatal incident are not allowed in case of any prejudice at a future inquest.
•(7.3c) Discussion will be at the discretion of the forum staff, however in most cases once the facts have been confirmed, a given thread will most likely be locked to prevent non factual speculation.
•(7.3d) Should an official report be released, a request can be made to a member of forum staff to have a link added to the original locked thread. For further discussion after an official report has been released, a new thread should be started.

Given that this type of incident/event will be subject to official lines of enquiry and/or investigation, it is important that we do not allow this forum to become involved with speculation that would detract from the facts. Information may or may not be found within websites elsewhere on the internet - just because it's on another website, it doesn't mean it is factually correct or that we'll allow it here; again the forum staff cannot 'police' other websites, but we are responsible for what appears on this forum.

The question about what is a pilot light has been moved to its own thread here.

[domh245]

The pilot dropping out only causes the motors to drop out - a loss of pilot light on its own won't demand a brake application..........so if a driver is coasting, they probably won't be aware straight away.

ah, Ok, but the OP did mention that the train was leaving clapham common, so surely he would have been accelerating, unless he was going NB in which case there is a low PSR there which could explain why "The train continued moving for a while before the driver noticed and stopped in the tunnel".

Why is it that I always end up answering my own Questions?

[caravelle]

Apr 22, 2013 17:19:14 GMT Colin said:

The pilot dropping out only causes the motors to drop out - a loss of pilot light on its own won't demand a brake application..........so if a driver is coasting, they probably won't be aware straight away.

The end door cut out is for preventing a door from opening - it won't bypass the pilot light circuit!!

The driver did do the correct procedure in terms of stopping and asking for a handle to be pulled if there is a door open via the PA, but I'm rather concerned that there is no mention of a member of staff being posted in the affected carriage for the journey to the next station.

As for how it happened, well I wouldn't mind knowing the answer too!!

I find it strange that the doors don't have an acessible manual by-pass that would allow it to be closed and locked by hand and deactivated and a pilot light jumper that would allow that door to send a closed signal after electrical fault provided it can be closed and deactivated mechanically/by hand. As a safety precaution the jumper could only be inserted after the deactivating handle is moved, etc...

Than take 2 enormous stickers and slap them on the door until the train can be seen to by a fitter or taken out of service.

That should take no more than 5-10 min and reduce delays.

[rincew1nd]

Other railway companies do have a similar system, doors out of use are locked and stickered as out of use. LU, however, simply takes the train out of service immediately; I presume because of a variety of problems caused when doors don't open infront of people (both inside and out).

[Chris M]

Apr 22, 2013 18:49:01 GMT caravelle said:

I find it strange that the doors don't [...] a pilot light jumper that would allow that door to send a closed signal after electrical fault provided it can be closed and deactivated mechanically/by hand. As a safety precaution the jumper could only be inserted after the deactivating handle is moved, etc...

I'm not sure about that. Unless the jumper could only be physically placed when the doors were closed and they could not be opened with it in place, then I can see it being accidentally left in place and thus the safety provided by he interlock not being present for that door.

As a separate question, how long does an override of the door interlock last?
If, as in this case a door fails between stations then interlock will need to be overridden to move the train to the next station for detraining (after all the correct procedures have been done of course). If the door interlock then couldn't be obtained after detraining, would it have to be overridden again in order to move the train to the depot or would the previous override still be in effect until actively cancelled?

[rincew1nd]

Apr 22, 2013 19:17:07 GMT Chris M said:

Apr 22, 2013 18:49:01 GMT caravelle said:

I find it strange that the doors don't [...] a pilot light jumper that would allow that door to send a closed signal after electrical fault provided it can be closed and deactivated mechanically/by hand. As a safety precaution the jumper could only be inserted after the deactivating handle is moved, etc...

As a separate question, how long does an override of the door interlock last?

In my mind it's a switch, possibly with a glass rod through it so you can tell if it has been activated.

Having had a quick scooch around the web the only thing I can find that is similar to my mental image are these:



The switches covered with the brass flaps.

[Deleted]

It's lucky it didn't happen when the train was full

[caravelle]

Quoting Chris M

I'm not sure about that. Unless the jumper could only be physically placed when the doors were closed and they could not be opened with it in place, then I can see it being accidentally left in place and thus the safety provided by he interlock not being present for that door.

That's why I've written:

As a safety precaution the jumper could only be inserted after the deactivating handle is moved, etc...

So, we've got 3 scenarios:

Mechanical door actuation failure, electrical door failure (sensing or command) and both failures (improbable yet possible):

Solutions:

Mechanical door failure and electrical door failure (command): If it's a simple failure and the kinematics are ok then unclutch the door (or somehow disengage the system), close, lock and deactivate it. Pilot circuit should work.

Electrical door failure (sensing) and and both failures: This affects the pilot circuit and the door should be closed as above (or automatically) and a jumper would be inserted. Again this jumper can only be inserted if the door is mechanically locked and it's power deactivated (whether electric or pneumatic) so you can only reactivate the door by physically taking the jumper out.

Hope I've explained it better this time.

[Deleted]

Apr 22, 2013 18:28:23 GMT domh245 said:

unless he was going NB in which case there is a low PSR there

I can confirm that it was a NB train.

@spinba11 said:

It's lucky it didn't happen when the train was full

Yes, thankfully this was not a serious incident as nobody was near the set of doors at the time.

caravelle said:

So, we've got 3 scenarios:

Mechanical door actuation failure, electrical door failure (sensing or command) and both failures (improbable yet possible):

The doors did close after detraining at the next stop, so this would suggest that it was an electrical failure rather than a mechanical?

[North End]

Apr 22, 2013 13:50:01 GMT tubepassenger said:

On departure from Clapham Common, the last set of double doors on this Northern Line train opened. The train continued moving for a while before the driver noticed and stopped in the tunnel.



What could cause this malfunction? The train op spent a long time trying to fix the problem, but the doors wouldn't budge.

It is not appropriate to post in detail, however rest assured this incident has been the subject of an extremely thorough investigation.

What I will say is that the train behaved in accordance with its design.

Those with a more detailed knowledge of train equipment and design may be able to work out what happened, however I would request this is not further discussed on this forum in order to avoid reoccurrence.

[rincew1nd]

In accordance with the request above and in accordance with the forum rules (as quoted above) this thread is now locked.