Croydon Tram Crash

[AlterEgo]

Sorry if this has been discussed, but not going back through 36 pages to check: cant agree with them naming the driver. He could be innocent as far as we all know.

It is standard practice with most criminal investigations.
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Interim RAIB report published.

https://www.gov.uk/government/news/interim-report-fatal-tram-accident-croydon

 

[gavin]

Tram that derailed in Croydon killing seven people was travelling at 43.5mph in a 12mph zone

 

[JaJaWa]

"30 A tram approaching the Sandilands Junction area from Lloyd Park at 80 km/h (50 mph) would need to brake at its full service rate of 1.3 m/s2 approximately 180 metres before the speed restriction board in order to be travelling at 20 km/h (12.5 mph) when the board was reached.
31 Initial analysis of the tram’s OTDR indicates that some braking was applied in the 180 metres before the 20 km/h (12.5 mph) speed restriction board, but this was only suf cient to reduce the tram’s speed from 80 km/h (50 mph) to approximately 70 km/h (43.5 mph) by the time the tram passed the board and entered the curve on which the accident occurred."

 

[Deepgreen]

I believe that a check rail on the outer rail would inhibit this, because if the vehicle does tilt significantly and pivot about the outer wheeltreads, the outer wheel flanges would be inhibited from tilting further by starting to rub, and then be restrained, by the outer check rail. Even better if the check rail can be somewhat proud of the running rails, as much as the suspension etc allows.

If anything, an outer check rail would increase the likelihood of overturning, as the vehicle would be prevented from leaving the running rails and simply travelling upright at a tangent to the curve, because the added check rail would merely introduce another impedance to the lateral movement of the wheels and induce an overturning force (or, to put it extremely basically; like tripping the tram up rather than letting it slide upright).

 

[mirodo]

Detailed examination of the tram has not yet been possible. However, the RAIB’s
initial investigation has not indicated any malfunction of the tram’s braking system.

A tram approaching the Sandilands Junction area from Lloyd Park at 80 km/h (50 mph) would need to brake at its full service rate of 1.3 m/s2 approximately 180 metres before the speed restriction board in order to be travelling at 20 km/h (12.5 mph) when the board was reached.

Initial analysis of the tram’s OTDR indicates that some braking was applied in the 180 metres before the 20 km/h (12.5 mph) speed restriction board, but this was only sufficient to reduce the tram’s speed from 80 km/h (50 mph) to approximately 70 km/h (43.5 mph) by the time the tram passed the board and entered the curve on which the accident occurred.

 

[Domh245]

A brief summary then from that report:

Tram went into the corner at about 70kph
Once derailed, travelled about 25m on it's side
Right hand side of tram was severely damaged
CCTV may not have been working at time of incident
Brake system wasn't malfunctioning
Initial analysis suggests some braking carried out in the 180m before the 20kph limit started, but only slowed tram by 10kph

Urgent Safety Advice: "the RAIB advises London Trams and Tram Operations Ltd to jointly take measures to reduce the risk of trams approaching Sandilands Junction from the direction of New Addington at an excessive speed. Options for consideration should include the imposition of a further speed restriction before the start of the existing 20 km/h speed restriction around the curve and/or additional operational signs"

 

[bradders1983]

So some braking occured, thats the blackout excuse the Union will be advising him to use out of the window then.

 

[Deepgreen]

There has been much mention of passengers being injured by being thrown out of derailed vehicles' windows, but from the pictures that I have seen, all the windows on the upward-facing side of the crashed tram appear to be intact. Is it safe to assume from this that passengers were not ejected in this case?

 

[Domh245]

There has been much mention of passengers being injured by being thrown out of derailed vehicles' windows, but from the pictures that I have seen, all the windows on the upward-facing side of the crashed tram appear to be intact. Is it safe to assume from this that passengers were not ejected in this case?

The windows on the LHS/Upwards facing side would be fine, but all of the windows on the RHS/downwards facing side will have all been broken if the tram was sliding along the ground and over the other track for 25m. Passengers almost certainly would have been ejected (in the removed from the vehicle sense) through the holes in the RHS of the tram were windows used to be which is how they became stuck underneath the tram.

 

[SPADTrap]

So some braking occured, thats the blackout excuse the Union will be advising him to use out of the window then.

No. Be careful what you say.

 

[507 001]

So some braking occured, thats the blackout excuse the Union will be advising him to use out of the window then.

Of course not, he could have blacked out, come around and then put the brake in for all we know.


Except we don't know. Anything.

:roll:

 

[AlterEgo]

So some braking occured, thats the blackout excuse the Union will be advising him to use out of the window then.

It *could be* that the driver suffered a blackout after partially braking.

That he had started braking indicates he was aware of his position on the track and aware of the incoming corner - the question is, was this braking at the appropriate point, within the tunnel, or was it hard, last-minute emergency braking as he looked up from his phone (or other distraction)?

 

[evergreenadam]

"30 A tram approaching the Sandilands Junction area from Lloyd Park at 80 km/h (50 mph) would need to brake at its full service rate of 1.3 m/s2 approximately 180 metres before the speed restriction board in order to be travelling at 20 km/h (12.5 mph) when the board was reached.
31 Initial analysis of the tram’s OTDR indicates that some braking was applied in the 180 metres before the 20 km/h (12.5 mph) speed restriction board, but this was only suf cient to reduce the tram’s speed from 80 km/h (50 mph) to approximately 70 km/h (43.5 mph) by the time the tram passed the board and entered the curve on which the accident occurred."

That is pretty damning. Basically by the time you reached the speed restriction board advertising the need to drop speed dramatically, there would be no time to do so. Is that normal practice on light rail systems and on the railways? Is the driver just expected to remember where all the speed restrictions are and where exactly to start braking?

 

[AlterEgo]

No. Be careful what you say.

Indeed. Allegations that the Union will be "advising" him to claim a blackout are incredibly speculative, probably untrue, and above all unhelpful.
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That is pretty damning. Basically by the time you reached the speed restriction board advertising the need to drop speed dramatically, there would be no time to do so. Is that normal practice on light rail systems and on the railways? Is the driver just expected to remember where all the speed restrictions are and where exactly to start braking?

That is not quite what that passage says or implies.

 

[Domh245]

That is pretty damning. Basically by the time you reached the speed restriction board advertising the need to drop speed dramatically, there would be no time to do so. Is that normal practice on light rail systems and on the railways? Is the driver just expected to remember where all the speed restrictions are and where exactly to start braking?

You should be doing the advertised speed as the cab passes the sign, and similarly shouldn't speed up again until the rear cab is past the sign for an increase in line speed. Drivers are expected to know where all of the speed restrictions are - their extensive route knowledge is one of the reasons it takes as long as it does to train them.

 

[bradders1983]

No. Be careful what you say.

Why? Will I have ASLEF/RMT rummaging through my bins and stalking me? :roll:

 

[AlterEgo]

Why? Will I have ASLEF/RMT rummaging through my bins and stalking me? :roll:

They wouldn't need to do either to sue you for libel.

It would be really helpful if people didn't try and point fingers and make allegations for which there is no evidence.

 

[Hornet]

Presumably the Luas uses old-Metrolink-style railway block signalling off the street sections, then?

No.

"The Luas network will not have signalling in the conventional railway sense."

http://www.irrs.ie/Journal 153/153 LUAS.htm

Part of my remit when working on the LUAS project was the Road/Rail signalling interfaces.

 

[neonison]

To read the interim report:

https://assets.publishing.service.g...d14ae00000a/IR012016_161116_Sandilands_Jn.pdf

13. …and then passes through Sandilands tunnels (comprised of three closely spaced tunnels with a total length of 512 metres), before emerging into a cutting approximately 100 metres before the left-hand curve on which the accident occurred. The curve has a radius of approximately 30 metres.

15. …A reflective board denotes the commencement of the 20 km/h speed restriction; it is located approximately 30 metres before the point where the derailment occurred.

31. Initial analysis of the tram’s OTDR indicates that some braking was applied in the 180 metres before the 20 km/h (12.5 mph) speed restriction board, but this was only sufficient to reduce the tram’s speed from 80 km/h (50 mph) to approximately 70 km/h (43.5 mph) by the time the tram passed the board and entered the curve on which the accident occurred.

The speed restriction board comes before the curve and the cutting is only 100 metres long; this seems to indicate that there was a partial brake application whilst the tram was still in the tunnel.

30. A tram approaching the Sandilands Junction area from Lloyd Park at 80 km/h (50 mph) would need to brake at its full service rate of 1.3 m/s2 approximately 180 metres before the speed restriction board in order to be travelling at 20 km/h (12.5 mph) when the board was reached.

Which would also indicate that the speed restriction board would need to be sighted from well within the tunnel to be of any use for a driver wholly relying on 'line-of-sight'.


.

 

[2HAP]

Doesn't the speed restriction board work like those on the roads?

You are supposed to have slowed down to 30mph when you reach the 30 sign, not start slowing down once you reach the sign.

 

[neonison]

Doesn't the speed restriction board work like those on the roads?

You are supposed to have slowed down to 30mph when you reach the 30 sign, not start slowing down once you reach the sign.

I'd imagine that to be the case but on the road there is sufficient time and distance for a motor vehicle driver to react. Of course the rule which is drummed into drivers is to travel only as fast as you can see to stop safely and short of any obstruction on your own side of the road. If one sticks to that one should never be caught out even on unfamiliar roads.

The tram protocol seems to embrace the philosophies of both 'line-of-sight' and 'route knowledge' which may not fit well in the same frame of operating parameters.

.

 

[littlerock]

In reply to earlier comment, it was reported by other passengers that someone was thrown out of the window when the train came off the rails and that when it fell on its side, the windows came out (smashed.) There are several reports of passengers being dragged along the ground as it skidded. There were also passengers trapped under the train; the fatal injuries seem to have been mainly caused by the windows being destroyed in the impact. I assume all the windows on the underside of the train are gone.
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Photo of the tram I believe
https://www.theguardian.com/uk-news...h-victims-named-investigation-continues#img-1
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Reports that the CCTV was not working. It never does......when you need to see it.

 

[MarkyT]

I just noticed from this youtube video thread https://youtu.be/lhuogCAh6Pg?t=14m2s that the speed signs are very small and inconspicuous indeed, not like road signs at all. I assume that is so on shared road sections different speeds can be displayed for road and rail vehicles. There's no advance warning sign whatsoever on approach to this major speed restriction and I doubt the readability of the speed sign is any more than 100m or so. In the video the train starts slowing down about half way through the last tunnel which corresponds well with the RAIBs statement that normal service braking distance for the speed reduction is about 180m.

 

[bramling]

That is pretty damning. Basically by the time you reached the speed restriction board advertising the need to drop speed dramatically, there would be no time to do so. Is that normal practice on light rail systems and on the railways? Is the driver just expected to remember where all the speed restrictions are and where exactly to start braking?

On a heavy railway, the driver is expected to know the route, and know where to slow down.

The tram system works on the same basis, although the superior braking capability of the trams and "line of sight" driving make it more forgiving, although the flip side of the coin is that there generally many more changes of speed than a heavy rail driver experiences.

One thing I've noticed having watched a cab ride of the system, the outbound (i.e. towards New Addington) exit from the tunnels does not require any immediate reduction in speed. To me, bearing in mind that driving on this system must be pretty repetitive, this does introduce a risk of someone getting their location confused. Any Underground driver will tell you that much driving is done on "autopilot", and it's very easy under such circumstances to simply forget where you are. One way or the other, my view is there definitely needs to be some kind of engineered safeguard.

 

[neonison]

I just noticed from this youtube video thread https://youtu.be/lhuogCAh6Pg?t=14m2s that the speed signs are very small and inconspicuous indeed, not like road signs at all. I assume that is so on shared road sections different speeds can be displayed for road and rail vehicles. There's no advance warning sign whatsoever on approach to this major speed restriction and I doubt the readability of the speed sign is any more than 100m or so. In the video the train starts slowing down about half way through the last tunnel which corresponds well with the RAIBs statement that normal service braking distance for the speed reduction is about 180m.

.
It's difficult to compare the visibility of the sign:
1. A video with narrow exposure latitude taken in the contrast of sunny day.
2. The vision of a driver in the dark in torrential rain through the wiper-pattern of a rain splattered windscreen and the reflection of that sign amongst the glare of other reflections.
However, it seems unlikely that a driver could rely on 'line-of-sight' alone on this approach.


.

 

[Shaw S Hunter]

On a heavy railway, the driver is expected to know the route, and know where to slow down.

It's worth adding that the existence of TPWS on the mainline railway allows for the fitment of TPWS-OSS (Overspeed Sensor System) on the approach to any permanent significant reduction in line speed thereby ensuring, at least at the position of the OSS grid, that a train has reduced speed to a certain level. It's not infallible but given the that a TPWS induced brake application is treated with a seriousness not far short of a SPAD drivers have the position of OSS grids ingrained along with other route knowledge and ensure they brake accordingly.

One way or the other, my view is there definitely needs to be some kind of engineered safeguard.

Given that this incident is starting to gain some political attention it's difficult to see how such provision can be avoided.

 

[507 001]

That is pretty damning. Basically by the time you reached the speed restriction board advertising the need to drop speed dramatically, there would be no time to do so. Is that normal practice on light rail systems and on the railways? Is the driver just expected to remember where all the speed restrictions are and where exactly to start braking?

Yes, it's called route knowledge.

To read the interim report:

https://assets.publishing.service.g...d14ae00000a/IR012016_161116_Sandilands_Jn.pdf

13. …and then passes through Sandilands tunnels (comprised of three closely spaced tunnels with a total length of 512 metres), before emerging into a cutting approximately 100 metres before the left-hand curve on which the accident occurred. The curve has a radius of approximately 30 metres.

15. …A reflective board denotes the commencement of the 20 km/h speed restriction; it is located approximately 30 metres before the point where the derailment occurred.

31. Initial analysis of the tram’s OTDR indicates that some braking was applied in the 180 metres before the 20 km/h (12.5 mph) speed restriction board, but this was only sufficient to reduce the tram’s speed from 80 km/h (50 mph) to approximately 70 km/h (43.5 mph) by the time the tram passed the board and entered the curve on which the accident occurred.

The speed restriction board comes before the curve and the cutting is only 100 metres long; this seems to indicate that there was a partial brake application whilst the tram was still in the tunnel.

30. A tram approaching the Sandilands Junction area from Lloyd Park at 80 km/h (50 mph) would need to brake at its full service rate of 1.3 m/s2 approximately 180 metres before the speed restriction board in order to be travelling at 20 km/h (12.5 mph) when the board was reached.

Which would also indicate that the speed restriction board would need to be sighted from well within the tunnel to be of any use for a driver wholly relying on 'line-of-sight'.


.

Placement of the speed board is absolutely, 100% irrelevant.

There are numerous boards on Metrolink that are out of your normal line of sight. We still know they're there.

Just like we'd still know there is a nigh on 90 degree bend ahead.

It's called route knowledge.

Route knowledge is essential. Teams don't stop like cars. They don't stop like busses either. They're actually pretty slow to stop so you do need to know braking points and speed restrictions like the back of your hand.

 

[Groningen]

Excessive speed caused Croydon tram derailment

UK: On November 16 the Rail Accident Investigation Branch published its interim report into a fatal derailment on the Tramlink light rail network in Croydon, south London, which had taken place at around 06.07 on November 9.

The report provides key information and urgent safety advice ahead of the completion of RAIB’s detailed investigation and the publication of its final report, likely to take some months. Separate investigations are being undertaken by the British Transport Police, Office of Rail & Road and other interested parties.

The derailment occurred on a curve of approximately 30 m radius on a section of fully-segregated line near Sandilands Junction. The maximum permitted speed approaching the curve is 80 km/h, with a reflective board around 30 m from the point of derailment marking the start of a 20 km/h speed restriction through the curve.

RAIB’s review of the on-train data recorder has found that Bombardier Flexity CR4000 tram 2551 entered the left-hand curve at approximately 70 km/h. It then derailed and fell onto its right-hand side, travelling for approximately 25 m before stopping. The side of the vehicle in contact with the ground was severely damaged, and there was also damage to the track and lineside equipment.

The driver and approximately 60 people were on the tram, with seven passengers suffering fatal injuries and a further 51 being taken to hospital; eight had serious or life-threatening injuries.

RAIB has found no evidence of any track defects or obstructions which could have contributed to the derailment. Detailed examination of the tram has not yet been undertaken, but the initial investigation has not indicated any malfunction of the braking system.

RAIB said trams generally operate on line-of-sight principles, with no requirement for advance warnings of speed restrictions or for speed control systems to be installed. The data recorder shows that that some braking was applied in the 180 m before the speed restriction board, but this only reduced the speed from 80 km/h to 70 km/h by the time the tram had passed the board.

RAIB has issued urgent safety advice saying that before the junction reopens for passenger service Transport for London’s London Trams unit which manages the network, and FirstGroup subsidiary Tram Operations Ltd which operates the trams, should ‘jointly take measures to reduce the risk of trams approaching Sandilands Junction from the direction of New Addington at an excessive speed. Options for consideration should include the imposition of a further speed restriction before the start of the existing 20 km/h speed restriction around the curve and/or additional operational signs.’

Thanking RAIB for its interim report, FirstGroup CEO Tim O’Toole said he ‘would like to reiterate how shocked and saddened we are by the tragic incident’. He said FirstGroup would ‘continue to provide full support’ to the ongoing investigation, and was ‘working with Transport for London to follow the RAIB’s advice and provide clear instruction on this to our drivers.’

Commissioner of Transport for London Mike Brown said test trams had now been operated over the section of line damaged in the accident, following repairs. ‘We will follow RAIB’s advice and, before service is resumed, will implement additional temporary speed restrictions and associated signage near Sandilands to supplement existing safety arrangements’, he said. ‘We are continuing to carry out a thorough safety assessment and are taking the advice of an independent panel of tram experts. We will only resume services for the local community once that rigorous assurance process has been completed.’

Source: http://www.metro-report.com/news/ne...ive-speed-caused-croydon-tram-derailment.html

 

[bramling]

Source: http://www.metro-report.com/news/ne...ive-speed-caused-croydon-tram-derailment.html

So a week to not really tells us anything we didn't already know. I'd have liked to have seen a bit more detail as to what the driver's actions were, which must surely by now be clear from the download.

One thing, the fact that RAIB have felt the need to issue urgent safety advice surely makes the driver's position more secure, as long as he hasn't been reckless. Let's hope this holds true.

 

[Groningen]

Do not blaim me.