Croydon Tram Accident

[coachmann]

Exactly. Double deck buses have had to undergo a tilt test since time immemorial but it doesn't stop them turning on their sides in the wrong circumstances. So often this proves fatal for the vehicle body and sometimes the chassis.

[royaloak]

 

I find the way the BBC habitually turn to Christian Wolmar for comment regarding anything involving rail-borne transportation quite scary.  Has he got compromising photos of the Director General or something?

 

I think they should add a disclaimer: other rail experts are available.

I feel the 'other' is not needed, he might know his rail history but his knowledge of current rail operations is next to useless, my 10 year old probably knows more than Wolmar on that subject.

[Southernman46]

My 4 pennyworth - apologies if any I say has been said previously ....................

 

I feel for the poor driver - he didn't go to work that day intending to cause death and suffering - whatever the circumstances (and I do sincerely hope it wasn't his fault) - he will have to live with it on his conscience for the rest of his days.

 

The slab sided nature of the trams might have contributed - when the windows in contact with the rails & ground break and maybe the doors also become come displaced open depositing the unfortunate occupants between tram and ground, well  ............  and trams are full of very hard solid things like vertical poles that will serious damage soft things like a human flying through the air which the inertia of even a relative low speed sudden deceleration will launch ..............

 

but I am no expert on the mechanism of deaths / injurys in rail accidents - something I've managed to avoid thankfully.

 

Rail travel is still an enormously safe form of transport regardless

[Derekl]

And Wolmar was simply a broadsheet journo and bandwagon railway-basher in the past. I have no idea where he became respectable, let alone an authority.

 

Are you chaps unaware that he has published a number of well researched and regarded books on railway issues, here and elsewhere? It is quite legitimate to seek his views on rail related issues - I also can't find much disagreement with him in this case - he has pointed out that trams are inherently safe and warned against knee jerk reaction, which seems reasonable to me and to a number of other contributors.

[lanchester]

My 4 pennyworth - apologies if any I say has been said previously ....................

 

I feel for the poor driver - he didn't go to work that day intending to cause death and suffering - whatever the circumstances (and I do sincerely hope it wasn't his fault) - he will have to live with it on his conscience for the rest of his days.

 

The slab sided nature of the trams might have contributed - when the windows in contact with the rails & ground break and maybe the doors also become come displaced open depositing the unfortunate occupants between tram and ground, well  ............  and trams are full of very hard solid things like vertical poles that will serious damage soft things like a human flying through the air which the inertia of even a relative low speed sudden deceleration will launch ..............

 

but I am no expert on the mechanism of deaths / injurys in rail accidents - something I've managed to avoid thankfully.

 

Rail travel is still an enormously safe form of transport regardless

I don't think this has been mentioned, apologies if I have missed it, but 'arresting' someone in these sort of circumstances works both ways: the person involved is subject to a laid down legal process, which can be challenged if not respected; and the media are aware that there is a possibility that charges might be forthcoming in which case their ability to comment is rightly curtailed. OK they are allowed to say what they like before any charges are put, but the respectable media will be rather more cautious than otherwise. So in some ways, at least, being 'arrested' actually protects the individual, and helps assure that proper procedures are gone through.

[royaloak]

Are you chaps unaware that he has published a number of well researched and regarded books on railway issues, here and elsewhere? It is quite legitimate to seek his views on rail related issues - I also can't find much disagreement with him in this case - he has pointed out that trams are inherently safe and warned against knee jerk reaction, which seems reasonable to me and to a number of other contributors.

That might be your opinion, having tried to read a few of his books I couldnt possibly comment!

Edited November 11, 2016 by royaloak

[Derekl]

I've read his books.  Quite a lot of factual errors.  I think he relies on a team of researchers who obviously do not an engineering or scientific background.

His books have now gone down to the local Oxfam bookshop to make way for something better on bookshelves.

Peterfgf

 

I hold no brief for Mr Wolmar, but I do find this sort of comment not very useful: "quite a lot of factual errors": maybe, but are the errors his or your assessment since you are more likely to be wrong: name a few if you want to make a point with any validity. It might be worth checking that you actually are right before doing so, though.

[meil]

Exactly. Double deck buses have had to undergo a tilt test since time immemorial but it doesn't stop them turning on their sides in the wrong circumstances. So often this proves fatal for the vehicle body and sometimes the chassis.

Actually all public service vehicles have to pass a tilt test. Buses (double or single deck) and coaches. Of course what a bus can do that a tram can't is skid sideways. This can enable a bus to remain standing. This is not available to a tram.

 

If you know some technical details the toppling speed of the tram is easily calculated.

[Derekl]

That might be your opinion, having tried to read a few of his books I couldnt possibly comment!

Ah well, maybe one day you will try harder

[RJS1977]

Whilst agreeing with Woolmar in this instance, it's probably about the first time! I've found his magazine articles tedious and repetitive, irrespective of the subject of the article.

 

The level of his research can be seen in his ill-fated attempt to break the Tube Challenge record earlier this year. It was readily apparent that he hadn't contacted Guinness for confirmation of the current record or of the rules because his website quoted an earlier record as the time to beat, and he broke at least two rules in the process (not using the District Line during his visit to Kensington Olympia, and counting a non-stop pass-through of Tottenham Court Road as a visit).

[JDW]

My 4 pennyworth - apologies if any I say has been said previously ....................

 

I feel for the poor driver - he didn't go to work that day intending to cause death and suffering - whatever the circumstances (and I do sincerely hope it wasn't his fault) - he will have to live with it on his conscience for the rest of his days.

 

The slab sided nature of the trams might have contributed - when the windows in contact with the rails & ground break and maybe the doors also become come displaced open depositing the unfortunate occupants between tram and ground, well  ............  and trams are full of very hard solid things like vertical poles that will serious damage soft things like a human flying through the air which the inertia of even a relative low speed sudden deceleration will launch ..............

 

but I am no expert on the mechanism of deaths / injurys in rail accidents - something I've managed to avoid thankfully.

 

Rail travel is still an enormously safe form of transport regardless

 

Yes, I thought the same about the potential cause of deaths, once the tram is on its side, it effectively has one large glass floor, with little solid for people to fall on to - even more so than a bus or a train, as the proportion of the windows in relation to the rest of the bodyside is quite high.  It still shocks me though that it was able to roll over like that, even with the weight of equipment on the roof, the weight of bogies, floor, etc, plus passengers (15 people ~ 1 tonne) is not insignificant.  

 

Picking up on another point, as someone who drives buses for a living, I know that you can get a double decker around a corner surprisingly quickly with no risk of it rolling.  What would happen if you hit a kerb at the same time though is another thing altogether.  But with a tram (or articulated bus), unlike a train, there isn't much "twist" along the length of the tram, the sections being joined by turntables that can turn left/right and hinge up/down, but the vehicles stay in (approximately) the same horizontal plane, so unlike a train, the first section couldn't roll over, then take the next one with it.  If anything, I'd have expected the following sections to help keep it upright - unless of course the front did make it around the corner, and the rear "whipped" out, pulling the rest with it, something which we can't know until RAIB publishes its full report, and at any rate, it matters little to the majority of us exactly how it left the rails and rolled, the important thing is to find out why it was travelling so quickly in the first place.  Though sadly, none of that will bring back the poor souls who lost their lives this time.   

 

But yes, its all very sad, for all involved, and hopefully a very freak, one-off accident.

[PenrithBeacon]

David, the vehicle stability depends on a contact surface of no bigger then a dime (or similar, very small), e.i. the wheels on the rail heads. If that condition is fulfilled it's stable while moving, even in curves. But only up to a certain speed. Surpass that limit and centrifugal forces that affect the vehicle at its centre-point of gravity will shift it to outside the wheelbase and topple the vehicle. On low floor trams like the Croydon ones, that centre-point is well above the wheels due to the equipment on the roof. If, however, the precondition of wheels on the rail is no longer met, anything goes, really.

Really not sure about your point re rail contact. Don't think it's relevant in these circumstances. My point is that when a coach leaves the rail it ought to stay up right and unless the conditions are truly extreme it is a design failure if it doesn't.

 

Echoing an earlier post we ought also to be thinking of the driver as well as the hurt, the deceased and their friends and family. Modern day working shifts are such that that fatigue could easily have played a key role in this matter.

 

I'm sure the RAIB will get to the bottom of it.

 

Regards

[Derekl]

I don't think this has been mentioned, apologies if I have missed it, but 'arresting' someone in these sort of circumstances works both ways: the person involved is subject to a laid down legal process, which can be challenged if not respected; and the media are aware that there is a possibility that charges might be forthcoming in which case their ability to comment is rightly curtailed. OK they are allowed to say what they like before any charges are put, but the respectable media will be rather more cautious than otherwise. So in some ways, at least, being 'arrested' actually protects the individual, and helps assure that proper procedures are gone through.

 

The driver was arrested on suspicion of manslaughter, essentially causing death by negligence (acting in such a way as to cause a foreseeable risk of death). He has not been charged as suggested above, but has been arrested and now released on police bail, which means that he has agreed to present himself at a police station at some date in the future. Once so arrested, he can only be interviewed under caution and with the advice and in the presence of a solicitor if he so chooses, the interview(s) being taped, which affords him some protection. The alternative was to interview him under caution, without arrest. That can only be done by agreement, but I doubt that as an issue here. In the circumstances, where the driver is responsible for a tram reported to be over speeding possibly causing the accident with multiple fatalities the police would come in for criticism for not arresting. I do not think it makes any difference as far as formal media comment is concerned. Informal media is largely unconstrained, in any event. 

 

I share the view of the original post on this particular topic - nobody goes to work to end with this sort of mayhem - we don't know exactly what happened, but he was in charge of the tram involved in the accident that resulted in deaths and injuries - whatever the cause (and it may be that he was not at fault) it must feel pretty awful. 

[royaloak]

Ah well, maybe one day you will try harder

Not going to happen, as a current mainline train driver I think I am well able to tell when Mr Wolmar is spouting crap about the job of driving a train, something he is also very good at putting into print!

 

I also have a fair understanding of signalling etc and he is less than accurate about that as well.

[royaloak]

David, the vehicle stability depends on a contact surface of no bigger then a dime (or similar, very small), e.i. the wheels on the rail heads. If that condition is fulfilled it's stable while moving, even in curves. But only up to a certain speed. Surpass that limit and centrifugal forces that affect the vehicle at its centre-point of gravity will shift it to outside the wheelbase and topple the vehicle.

A small correction, its the flange that keeps the wheelset on the rails (in this case), not the contact patch of the tread.

 

I agree completely with the rest of your post.

Edited November 11, 2016 by royaloak

[Derekstuart]

I wasn't aware that single deck vehicles have to undergo tilt testing (but that might have been changed with eu directive 2007/46/EC regarding type approval- and should be changing back again in 2 years).

 

What single deck vehicles do have to pass is R.66 rollover testing, which broadly speaking requires that the bodywork suffers no more than X% deformity when on its side/roof (I am feeling de ja vu here). I have seen a 'decker on its side- pre R.66 regs- and it remained broadly intact. What was more common for structural failure was coaches as they tried to reduce the body weight to increase luggage/passenger loading.

 

Deckers will stay upright far more easily than most people realise- you have to really work hard to get one over. The decker mentioned above was from that very problem- he went around a bend far too quickly, clipped the NSR wheel, caused a skid and then the OSR wheel clipped the other kerb bringing it to a sudden stop- which is what put it over.

 

Not sure of the connection with tram incidents btw.

Exactly. Double deck buses have had to undergo a tilt test since time immemorial but it doesn't stop them turning on their sides in the wrong circumstances. So often this proves fatal for the vehicle body and sometimes the chassis.

 

Actually all public service vehicles have to pass a tilt test. Buses (double or single deck) and coaches. Of course what a bus can do that a tram can't is skid sideways. This can enable a bus to remain standing. This is not available to a tram.

If you know some technical details the toppling speed of the tram is easily calculated.

[Derekstuart]

That's just basic laws of physics. Inertia. An object will continue in whatever direction it is heading unless acted upon by an outside force.

 

Imagine driving your car around a roundabout too fast, the car will slip to the edge but likely stay on its wheels- but then you slide hard into the kerb and you form a turning motion vertically on your car, you are going onto your side or the roof.

 

Really not sure about your point re rail contact. Don't think it's relevant in these circumstances. My point is that when a coach leaves the rail it ought to stay up right and unless the conditions are truly extreme it is a design failure if it doesn't.

[andyman7]

Really not sure about your point re rail contact. Don't think it's relevant in these circumstances. My point is that when a coach leaves the rail it ought to stay up right and unless the conditions are truly extreme it is a design failure if it doesn't.

 

Echoing an earlier post we ought also to be thinking of the driver as well as the hurt, the deceased and their friends and family. Modern day working shifts are such that that fatigue could easily have played a key role in this matter.

 

I'm sure the RAIB will get to the bottom of it.

 

Regards

The forces apparent here are extreme - I don't know if you have used the section of line but I have and what you have is a fairly long straight section of line built on a rail alignment, which goes into a 90 degree curve that makes Hornby first radius curves look gentle. If that curve is taken at high speed the centrifugal force coupled with the pivoting effect of flanged wheels (no opportunity to skid sideways) is going to topple you over. 

It's telling that most witnesses to the aftermath initially assumed that the tram had been coming other way down the slope from Sandilands tram stop and had somehow split the points - it seemed inconceivable that a tram heading from New Addington could end up in that position, but once it was clear that was the case, the sheer violence of the derailment (and horrific casualty count) becomes more understandable.

[Edwin_m]

Really not sure about your point re rail contact. Don't think it's relevant in these circumstances. My point is that when a coach leaves the rail it ought to stay up right and unless the conditions are truly extreme it is a design failure if it doesn't.

It's a laws of physics thing.  Overturning will occur at a particular combination of factors including speed, curve radius, height of vehicle centre of gravity and track gauge.  It has been known with trains but only in very high speed derailments.  As trams have tighter curves overturning is possible at much lower speeds. 

 

Part of the difference with a bus is that the tram is forced by its rails into taking the tight radius turn, and if faster than the critical speed either a flange climb or an overturn becomes inevitable.  If a bus encounters a tight bend at speed then it might continue in a straight line, or nearly so, depending whether and how quickly the driver is able to get the steering wheel round.  This would probably result in collision with whatever is in the path of that straight line - less severe if it's an earth bank, more severe if a building (and we've had several buses ploughing into buildings in recent months).   But overturning seems much less likely with a bus. 

Edited November 11, 2016 by Edwin_m

[Fat Controller]

Out of curiousity, was there a check-rail on this curve?  I can think of other cases, where the curve radius is much greater, yet a check rail is fitted.

[Derekl]

Not going to happen, as a current mainline train driver I think I am well able to tell when Mr Wolmar is spouting crap about the job of driving a train, something he is also very good at putting into print!

 

I also have a fair understanding of signalling etc and he is less than accurate about that as well.

 

Ah, I see - I don't think he writes books about "how to drive a train", if he has, please point it out, but if that is what you were looking for I can see why you may find his writing wanting.

 

He discusses, very usefully, the development of the railway within society, with specific reference to the development of the railway and its influence on society with reference to development in specific countries/continents. If you are not interested in that, then you won't be interested in his books, but that doesn't make them "crap".

 

It is pointless saying he is less than accurate about signalling. He may be, but equally you may be: without examples of whee he is wrong and why, the comment is a waste of space.

[Derekstuart]

A mainline train driver is less accurate than a politician about railway signalling?

 

It is pointless saying he is less than accurate about signalling. He may be, but equally you may be: without examples of whee he is wrong and why, the comment is a waste of space.

[The Stationmaster]

Are you chaps unaware that he has published a number of well researched and regarded books on railway issues, here and elsewhere? It is quite legitimate to seek his views on rail related issues - I also can't find much disagreement with him in this case - he has pointed out that trams are inherently safe and warned against knee jerk reaction, which seems reasonable to me and to a number of other contributors.

 

He has published some absolute rubbish full of errors of fact and drawing conclusions which owe more to his ignorance or pre-conceptions than examination of the evidence or reality.

 

However I take a point made by various people above that in this particular instance he was actually quite sensible and said what many of us are thinking - that there should be no sort of knee jerk reaction to this incident (which might effectively start to load heavy rail ideas and standards onto light rail applications with consequential increase in costs etc).  Rather unusual for him I must admit but it was said and reported, presumably accurately.

[royaloak]

Ah, I see - I don't think he writes books about "how to drive a train", if he has, please point it out, but if that is what you were looking for I can see why you may find his writing wanting.

 

He discusses, very usefully, the development of the railway within society, with specific reference to the development of the railway and its influence on society with reference to development in specific countries/continents. If you are not interested in that, then you won't be interested in his books, but that doesn't make them "crap".

 

It is pointless saying he is less than accurate about signalling. He may be, but equally you may be: without examples of whee he is wrong and why, the comment is a waste of space.

I have read a few of his books and several of his articles, while (as I previously stated) his historical stuff is quite good, his knowledge about the modern railway is wanting.

 

But unfortunately you are not willing to believe anything bad against him so there is no point continuing!

[roythebus]

Wow, what a hornet's nest this has stirred up.

 

From time immemorial single and double deck buses have had to undergo a tilt test, tilting to 37 degrees if I remember correctly before they topple over. Whatever spec that is is immaterial. Buses have pneumatic tyres which allow quite an amount of give and additional "spring" which rail wheels don't usually have.

 

When I was doing train driver training many years ago we were told that curves had a 100% safety error built in, but as speed increases the lateral forces increase with the square root of the speed if that makes sense, maybe someone more technically minded than me can remember the formula.

 

There was a similar "high speed" crash not a million miles away at Eltham Well Hall in the 1970s when a class 47 on an excursion from Margate to Southend entered the 20 at about 45 with tragic results. From memory the cause was driver error, failing to brake in time. Part of the cause of that was a few too many in the Margate BRSA! The outcome was the fitting of AWS magnets before severe speed restrictions.

 

As for trams tipping over, a regular sport for that was the junction of Mitcham Lane and Southcroft Road at Tooting, where the line went down a steep hill on mitcham Lane and turned right into Southcroft Road. Several double deckers ended up on their sides in the bakers shop on the corner!

 

The first tram accident I remember in recent times was in Portsmouth of all places. I didn't believe the Portsmouth evening paper one day when returning from the Isle of Wight which read something like "policeman badly injured by tram in Portsmouth", a place that hadn't seen trams for years. The tram was one of those built in Italy for Manchester and was being transported on a low-loader from the ferry port. The policeman was directing traffic on a roundabout and was hit by the overhang of the tram!!

 

I also witnessed a safety exercise on the Croydon system before it opened, featuring a First Capital bus being hit by a tram in central Croydon. I've got some photos somewhere and will download them when I find them. The first thing the fire brigade done was to turn the current off; I pointed out the man in charge that may cause problems. No power=no compressors=no air to keep the air suspension inflated=possibility of further injuries to anyone trapped under the tram.