Trap and Drag at Bushey (26 March 2018)

[yorkie]

The Tring terminators under London Midland called at Bushey as they do with the current operator.

Yes, that's what I said.

 

[nuts & bolts]

Yes, that's what I said.

Oops you were referring to the Southern green machines

 

[Bayum]

Is a trap and drag only the passenger on the platform side?

 

[Intermodal]

Is a trap and drag only the passenger on the platform side?

What do you mean? If someone is inside the train they cannot be trapped AND dragged. I'm not sure I understand.

 

[yorkie]

Is a trap and drag only the passenger on the platform side?

Yes a 'trap and drag' incident only happens on the platform side, as they are effectively 'dragged' along the platform by the train.

 

[pt_mad]

The whole point about interlock raises questions about whether a guard or a dispatcher can reasonably be expected to see something small such as a bag strap potentially up to 10 coaches away in darkness. Providing everyone is behind the yellow line, where there is one, and you cannot see anything caught, and hazard lights extinguish the staff might assume the train safety check was complete. If a bag strap was trapped, the person was well back from the train and not showing any signs of being in trouble, and the item such as a strap or belt etc could not be seen then it's quite possible dispatch would be completed I'd say. I know there wasn't a strap involved in this case.

 

[Bletchleyite]

Some very interesting points and pictures of the RAIB managing to gain interlock with a (rather large) forearm trapped within the door. It seems like a forearm is possibly one of the most likely parts of the body to become trapped. Perhaps this piece of engineering needs revisiting?

The door edge rubbers on Class 350s are particularly thick and I can see how a smaller person's arm could get trapped with the door fully closed.

 

[Bletchleyite]

Was it envisaged when the exterior hazard lights were introduced for interlocking that they would indicate that nothing was trapped? Should imagine it could have been. What do they indicate now? That a door cannot close or has not closed. But they may extunguish when a door appears to have closed when in fact it hasn't successfully as there is an obstruction. So potentially they indicate when a door is definitely open, or that central locking has been released, or that passenger alarm has been activated. But they don't indicate whether a door is definitely closed, just that it may be closed.

I forget what the present term for them is but they are hazard lights. Being illuminated indicates that there is a hazard (and also usefully for passengers that the doors are released). Not being illuminated does not indicate the absence of one. If nothing else, the bulb could have failed. They are more a guide in the sense that a car indicator flashing indicates that someone is probably going to make a manoeuvre, but the absence of one does not indicate that they are not.

IIRC early designs of sliding door had edge sensors but these were found to be unreliable so they didn't last, and most if not all modern stock doesn't have these, relying on the guard (or driver) to be watching and to see a hazard.

 

[pt_mad]

I forget what the present term for them is but they are hazard lights. Being illuminated indicates that there is a hazard (and also usefully for passengers that the doors are released). Not being illuminated does not indicate the absence of one. If nothing else, the bulb could have failed. They are more a guide in the sense that a car indicator flashing indicates that someone is probably going to make a manoeuvre, but the absence of one does not indicate that they are not.

IIRC early designs of sliding door had edge sensors but these were found to be unreliable so they didn't last, and most if not all modern stock doesn't have these, relying on the guard (or driver) to be watching and to see a hazard.

I think another term for them is BILs, body side indicator lights. I've also heard some say 'one of the interlock lights hasn't gone out'. But as far as I know the RSSB rulebook still calls them exterior hazard lights even as recent as last December rulebook issue. Please correct me if I'm wrong on that I'm not 100 percent but I think that's the case.

 

[pt_mad]

On a more general note, with body side lights extuinguishing not meaning nothing trapped. Looking for something trapped is one thing, but let's say something small stuck at the bottom of a door mechanism, smaller than a bottle, and the door hadn't completely shut, maybe a few milimetres short. Would it be possible that the bodyside light would go out and interlock would be achieved? Because if the guard couldn't see anything trapped from the platform and all passengers were well clear, they wouldn't necessarily have a close up view of every door seal to the point that they could see a very slight gap in the seal or the rubbers, particularly if nothing was visibally trapped from the platform side?
If a belt were trapped from the inside of the train for example, how would a guard reasonably be expected to see this from anything more than 5 coaches away in the dark? Yet that could potentially mean a gap in the door seal which potentially could have it's own dangers.

 

[theageofthetra]

Some very interesting points and pictures of the RAIB managing to gain interlock with a (rather large) forearm trapped within the door. It seems like a forearm is possibly one of the most likely parts of the body to become trapped. Perhaps this piece of engineering needs revisiting?

So who signed this design off as being acceptable?

 

[Surreytraveller]

BIL = Body Interlock Light
If illuminated, it indicates that coach doesn't have interlock. It provides no indication whatsoever if anything is trapped in the doors or not. That's what the despatch procedure is for.

 

[Clip]

So who signed this design off as being acceptable?

How far do you go with the sensitivity of the door rubbers though?

I think they had massive problems with the new vic line trains because they were too sensitive - so what would you say, in your experience, would be the optimum sensitivity for the door rubbers - you will, of course, need to factor in such issues as loose clothing too which is very light compared to say a purse or a bag let alone a foot or a forearm - so what solution would you come up with?

 

[Bletchleyite]

On a more general note, with body side lights extuinguishing not meaning nothing trapped. Looking for something trapped is one thing, but let's say something small stuck at the bottom of a door mechanism, smaller than a bottle, and the door hadn't completely shut, maybe a few milimetres short. Would it be possible that the bodyside light would go out and interlock would be achieved? Because if the guard couldn't see anything trapped from the platform and all passengers were well clear, they wouldn't necessarily have a close up view of every door seal to the point that they could see a very slight gap in the seal or the rubbers, particularly if nothing was visibally trapped from the platform side?
If a belt were trapped from the inside of the train for example, how would a guard reasonably be expected to see this from anything more than 5 coaches away in the dark? Yet that could potentially mean a gap in the door seal which potentially could have it's own dangers.

Other than if some kind of wrong-side failure had occurred, I don't think you could get interlock with something trapped such that the door wasn't closed and locked properly. And a small gap in the seal with the door closed and locked properly does not pose any significant risk - the gap is smaller than the open window of a non-aircon train.

The risk is posed when the rubber edging is wide enough that something substantial can become trapped with the person attached to it outside and unable to retrieve it, or where something is trapped partially outside that could hit someone/something. Someone on the inside with a coat or similar caught is not at substantial risk, just inconvenience of being unable to take a seat (though it would still be a valid reason to use the passcom just in case).

 

[edwin_m]

So who signed this design off as being acceptable?

This report and the Newcastle one discuss that the standard is to insert an object of a particular size at right angles between the closing doors and confirm it is detected and they don't get interlock. In both cases the accident doors were re-tested and passed. There is a specific issue with Desiro doors that if the object is at an angle it defeats the detection. The report also notes that the later Desiro City has electric instead of air-operated doors which are claimed not to have this defect. But nobody seems to be suggesting retrofitting something better to the original Desiros, and I don't recall any mention of whether the standard has been beefed up for new trains.

 

[mrcheek]

I wonder if these issues occur because passengers think they can make the doors reopen if you stick a hand in the way, like you can on the Underground

 

[pt_mad]

BIL = Body Interlock Light
If illuminated, it indicates that coach doesn't have interlock. It provides no indication whatsoever if anything is trapped in the doors or not. That's what the despatch procedure is for.

The ironic thing being it's called interlock light, but it doesn't actually guarantee doors are physically interlocked in that something can be caught and it can still indicate interlocked.

 

[Dstock7080]

I wonder if these issues occur because passengers think they can make the doors reopen if you stick a hand in the way, like you can on the Underground

Only 2009 Stock (Victoria Line) and S Stock have obstacle detection on the Underground.

 

[Bletchleyite]

Only 2009 Stock (Victoria Line) and S Stock have obstacle detection on the Underground.

Though on older stock the doors close with very little force and can easily be held open.

 

[Esker-pades]

Though on older stock the doors close with very little force and can easily be held open.

As I have experienced when a disposable coffee cup got wedged in the Bakerloo Line doors. Caused 3 minutes of opening and closing before someone realised and kicked it out of the way.

 

[bengley]

BIL = Body Interlock Light
If illuminated, it indicates that coach doesn't have interlock. It provides no indication whatsoever if anything is trapped in the doors or not. That's what the despatch procedure is for.

To be slightly pedantic, it stands for Bodyside Indicator Light.

 

[theageofthetra]

How far do you go with the sensitivity of the door rubbers though?

I think they had massive problems with the new vic line trains because they were too sensitive - so what would you say, in your experience, would be the optimum sensitivity for the door rubbers - you will, of course, need to factor in such issues as loose clothing too which is very light compared to say a purse or a bag let alone a foot or a forearm - so what solution would you come up with?

Make the rubbers grip on one direction only. There are gloves used by climbers and those who work with ropes on ships which do exactly that.

 

[philthetube]

How far do you go with the sensitivity of the door rubbers though?

I think they had massive problems with the new vic line trains because they were too sensitive - so what would you say, in your experience, would be the optimum sensitivity for the door rubbers - you will, of course, need to factor in such issues as loose clothing too which is very light compared to say a purse or a bag let alone a foot or a forearm - so what solution would you come up with?

They did but it is sorted now and woks well

 

[HOOVER29]

I remember back when Crewe got remodelled in 1985.
I was tootling about on the station when I think a Liverpool to Euston service was leaving. All of a sudden there was much shouting. I turned to see a woman being dragged off the end of the platform holding her handbag which had got caught on the door opener. She finally let go when the train was crossing over to the main lines. Needless to say from being dragged her shoes/feet were a mess as were her shins. What happened to her I don’t know as I wandered off afterwards.

 

[Intermodal]

I remember back when Crewe got remodelled in 1985.
I was tootling about on the station when I think a Liverpool to Euston service was leaving. All of a sudden there was much shouting. I turned to see a woman being dragged off the end of the platform holding her handbag which had got caught on the door opener. She finally let go when the train was crossing over to the main lines. Needless to say from being dragged her shoes/feet were a mess as were her shins. What happened to her I don’t know as I wandered off afterwards.

Maybe the handbag had value exceeding that of her life? It's the only logical conclusion if she wouldn't let go! People do silly things.

 

[edwin_m]

People will tend to act rather irrationally in panic situations. If the initial thought was "I must get my handbag back" then they probably won't have the chance to stop and re-think as that gets more and more unlikely, until something significant changes like getting to the end of the platform. Rather like how people have taken their luggage with them in an emergency evacuation of a plane.

 

[ASharpe]

I wonder if these issues occur because passengers think they can make the doors reopen if you stick a hand in the way, like you can on the Underground

Well according to the RAIB report posted today and others in the past few years people do think that the doors reopen. However they don't on either the underground or the mainline unless the object is large enough.

47 The passenger stated that she thought the train doors would re-open, as she has seen this happen to other people on previous occasions. However, it is not clear whether this expectation was based on her experience with London Underground’s subsurface lines (paragraph 17), where the trains use a more sensitive door system that would have detected her bag (see paragraph 52). Nevertheless, similar expectations by members of the public have been observed in previous RAIB investigations8 . Research conducted by RSSB9 found that 58% of passengers believe that, if obstructed, train doors will automatically re-open like lift doors.

There needs to be education to passengers that doors will not reopen. Unfortunately on some LU trains all doors reopen and then close if on object is detected and this reinforces the idea on passengers throughout the train that doors always reopen. Changing those trains to only reopen the door with the obstruction would massively help the education of passengers and stop them from chancing it.

 

[the sniper]

A good number of people are even wiser to the game then that nowadays. They arrive late or want to hold the train for someone else, know if they just stand there with their hand on the train it shouldn't get dispatched, normally the doors will get reopened to allow them on as it wastes less time than someone having an argument with them, hoping that they'll move. If the train goes, they can report the Driver/Guard... And people wonder why Drivers don't want anything to do with the doors.

 

[Economist]

I've said before that I think the driver or guard should have a means of accessing the platform PA system to tell people to move away from the train or to remain behind the yellow line. Apparently, such a system is used in Germany.

In the Notting Hill Gate report, from paragraph 62 onwards there is a description and image which shows how easily passengers between the yellow line and the train can obscure the camera view of a trapped passenger. As a general rule, I won't depart when I can see during my train safety check that someone is between the yellow line and the train. The problem can be clearing the passengers back behind the yellow line when there are few ways of doing so.

Passengers complain about delays but a lot of the time, delays are caused by passengers putting themselves, or others in danger.

 

[edwin_m]

Some trams have external PA. Maybe trains should too.