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Author Topic: Collision between Azuma and HST at Neville Hill, Leeds, 13/11/2019  (Read 2984 times)
Bmblbzzz
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« Reply #15 on: November 14, 2019, 06:41:44 pm »

We can see the Azuma's rear lights in the broken fibreglass, so it seems as if the HST ran into the back of the Azuma.
After an accident, it's standard practice to switch on every red light available.  So I wouldn't rely on that to determine direction.

Also, on these Hitachi trains the Tail Lights are illuminated automatically whenever the driver keys out of the train - unless coupled, or overridden by the Emergency Headlight Switch.
Ah, thank you. That's two railway lighting things I've learnt today!
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« Reply #16 on: November 14, 2019, 06:42:44 pm »

We can see the Azuma's rear lights in the broken fibreglass, so it seems as if the HST ran into the back of the Azuma.

When the cab is locked out on the Azumas the tail lights illuminate. The cab was locked out to preserve i would imagine.

The HST was stationary, the Azuma has effectively ran into a 410 Ton wall
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stuving
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« Reply #17 on: November 14, 2019, 07:07:57 pm »

I'm quite relieved there was a bit of a mess.  Better a mess at the front where the energy of a collision is designed to be absorbed, than that energy being felt further back where passengers might be sat.

I agree, but am slightly alarmed by the derailment. I am, however, no expert.
The 800 was still “snaking” across a couple of sets of points at the point of derailment.  I think the HST was basically on almost straight track.  I expect that affected the derailment?

There is still something rather alarming about such a low-speed collision causing several coaches to derail. I hope it's down to the somewhat ramshackle track of the depot arrival line. While the rear of the train was still over the crossover, the HST was also partly on a curve. Which was moving doesn't really matter in the impact, nor do brakes; it's all down to mass distribution.

While the HST power car is roughly twice as heavy as a Mk 3 (70 vs 36 t), the 801's driving car is not so much lighter (48 t, if first class was at the other end, otherwise 52 t). Not having engines, the intermediate coaches are fairly light, but still heavier than Mk 3s (ca. 40 t, I'd guess). It's light vehicles needing to convey a large impact force that are at risk of jumping, and it's not obvious whether that applies here.

Railway safety has been improved in several places, of which train protection and structural integrity of vehicle body shells are two major ones. Keeping trains on the track, and upright even off it, are important too, at least for low and medium speed collisions (at high speeds there is no overall "solution"). More rigid couplings help in that, though articulation (shared/Jacobs bogies) is the best. that's why this looks alarming.

The 26 m coaches of the 801s do have a longer overhang at the ends than 23 m stock. That does increase the leverage of end force (whatever its direction) at the bogies, so I wonder if that is relevant. Also, the gap between coaches is particularly long - does that mean the coupling is longer between its fixings into the body at each end?
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IndustryInsider
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« Reply #18 on: November 14, 2019, 07:49:26 pm »

I expect the RAIB will look into everything.
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« Reply #19 on: November 14, 2019, 08:36:27 pm »

I expect the RAIB will look into everything.

I wouldn't be surprised if they do!
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« Reply #20 on: November 14, 2019, 10:50:14 pm »

I'm quite relieved there was a bit of a mess.  Better a mess at the front where the energy of a collision is designed to be absorbed, than that energy being felt further back where passengers might be sat.

I agree, but am slightly alarmed by the derailment. I am, however, no expert.
The 800 was still “snaking” across a couple of sets of points at the point of derailment.  I think the HST was basically on almost straight track.  I expect that affected the derailment?

There is still something rather alarming about such a low-speed collision causing several coaches to derail. I hope it's down to the somewhat ramshackle track of the depot arrival line. While the rear of the train was still over the crossover, the HST was also partly on a curve. Which was moving doesn't really matter in the impact, nor do brakes; it's all down to mass distribution.

While the HST power car is roughly twice as heavy as a Mk 3 (70 vs 36 t), the 801's driving car is not so much lighter (48 t, if first class was at the other end, otherwise 52 t). Not having engines, the intermediate coaches are fairly light, but still heavier than Mk 3s (ca. 40 t, I'd guess). It's light vehicles needing to convey a large impact force that are at risk of jumping, and it's not obvious whether that applies here.

Railway safety has been improved in several places, of which train protection and structural integrity of vehicle body shells are two major ones. Keeping trains on the track, and upright even off it, are important too, at least for low and medium speed collisions (at high speeds there is no overall "solution"). More rigid couplings help in that, though articulation (shared/Jacobs bogies) is the best. that's why this looks alarming.

The 26 m coaches of the 801s do have a longer overhang at the ends than 23 m stock. That does increase the leverage of end force (whatever its direction) at the bogies, so I wonder if that is relevant. Also, the gap between coaches is particularly long - does that mean the coupling is longer between its fixings into the body at each end?

9 car Azuma approx 431 tons, 2+9 HST approx 410 tons
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grahame
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« Reply #21 on: November 15, 2019, 06:43:34 am »

I expect the RAIB will look into everything.

I'm sure they will. It's an opportunity (and unplanned and unwelcome one, but one which must be taken) to look at the reaction in collision of an IET.  I'm sure it's all be simulated and worked through in theory but there's noting like the practical look too.   That look in addition to "how did they come to collide" in the first place!
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Oxonhutch
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« Reply #22 on: November 15, 2019, 09:44:08 am »

This incident, along with the buffer-stop collision at Long Rock Depot, makes me think that these IEPs have some unexpected behaviours - or should that be vices - when it comes to braking.
« Last Edit: November 15, 2019, 10:00:02 am by Oxonhutch » Logged
grahame
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« Reply #23 on: November 25, 2019, 09:06:17 pm »

Quote
RAIB report

"At about 21:40 hrs on Wednesday 13 November 2019, an empty passenger train approaching the maintenance depot at Neville Hill in Leeds, caught up and collided with the rear of another empty passenger train moving into the depot on the same track. The low speed movement of trains close together is permitted by the signalling system at this location. The leading train was travelling at around 5 mph (8 km/h) and the colliding train at around 14 mph (22 km/h). No one was injured in the accident.

"The colliding train was a 9-coach class 800 train, part of the Intercity Express Programme (IEP). Its leading end suffered significant damage during the collision. The second train was a High Speed Train (HST) set comprising 9 coaches and a class 43 locomotive at each end. The trailing class 43 locomotive on this train also suffered significant damage.

"As a result of the collision, the trailing bogie of the second and third coaches and the trailing axle of the fourth coach on the class 800 train, derailed to the right in the direction of travel.

"Our investigation will identify the sequence of events which led to the accident and the factors that contributed to its consequences. It will consider:

- The actions, training and competence of the staff involved

- The design and validation of the class 800 train, including the ergonomics of its cab, its crashworthiness performance and its resistance to derailment in collision scenarios

- Any underlying factors

"Our investigation is independent of any investigation by the railway industry, the Office of Rail and Road.

"We will publish our findings, including any recommendations to improve safety, at the conclusion of our investigation. This report will be available on our website."

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« Reply #24 on: November 18, 2020, 02:06:40 pm »

Report summary from https://www.gov.uk/government/news/report-132020-collision-and-derailment-at-neville-hill

Quote
At 21:41 hrs on 13 November 2019, an empty LNER Intercity Express Train, approaching the maintenance depot at Neville Hill in Leeds, caught up and collided with the rear of a LNER High Speed Train moving into the depot. The leading train was travelling at around 5 mph (8 km/h) and the colliding train at around 15 mph (24 km/h). No one was injured in the accident, but the trailing bogie of the second and third vehicles and the trailing wheelset of the fourth vehicle of the Intercity Express Train derailed to the right, by up to 1.25 metres.

The collision occurred because the driver of the Intercity Express Train was focused on reinstating an on-board system which he had recently isolated, instead of focusing on the driving task. This was exacerbated by him unintentionally commanding too much acceleration due to his lack of familiarity with the train.

The driver had isolated the on-board system at Leeds station because he had been unable to correctly set up the train management system. He had been unable to do this because ambiguous documentation from Hitachi, the train manufacturer, had led to LNER misunderstanding the required process for setting up the train management system when developing the content of its driver training programme.

The driver?s lack of adequate familiarity with the train probably arose because LNER had not recognised that his training needs were greater than for his peers.

The derailment occurred because the design of the Intercity Express Train is susceptible to derailment in low speed collisions. This susceptibility is related to the use of high-strength couplers with large freedoms of movement in pitch and yaw. These features were part of the train?s design. However, the impact of these features on the train?s resistance to derailment and lateral displacement in low speed collisions, was not considered by the train?s designers.

The crashworthiness standard used to design the Intercity Express Train did not specifically require consideration of the likelihood of derailment during collisions at lower than the 22.5 mph (36 km/h) specified design speed, nor did it include specific criteria for assessing the derailment performance. As such, the assessment and validation of the design did not identify any issues with these design features.

Full report (55 pages) at https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/935941/R132020_201118_Neville_Hill.pdf
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stuving
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« Reply #25 on: November 19, 2020, 11:10:12 pm »

That was an interesting read. I didn't see any convincing theory at the time as to why this train derailed so badly after a low-speed collision, so this was always a matter of waiting for the RAIB to tell us.

The basic dynamics of a train that has to stop very fast indeed, because it's hit something, is fairly simple. Each carriage body goes down at the front, and up at the back, and the high forces in the couplers then add to that effect and can lift the rear bogies off the track. It only takes a random initial yaw angle of any of the carriages to mean the same forces push those rear bogies sideways too. But that doesn't usually happen in low-speed collisions - but did this time - why?

What I hadn't realised was that the couplers have to collapse, and in most trains are designed to do so sacrificially (i.e. to protect the body shells). Hence in this case the RAIB identified that the failure of the couplers to collapse (shorten) was a primary cause of the derailment, and a design error. Exactly what should happen when the gap between the carriages has reduced to zero was not made clear (because it wasn't part of the accident). Presumably they should lock in some way, if only by being scrunched into each other.

The lengths of the body and the coupler also were not as significant as I imagined, though the gap between the carriage ends being so large did allow a lot more movement up and sideways than otherwise.

The cause of the accident was operational, though Hitachi's software played a part in the driver's errors, but how the train behaved is all down to Hitachi's design. And that does look embarrassing for them as a major train maker. While the standards and requirements may not have told them to worry about low-speed collisions, they should have know it was needed. The first technical director I had to present projects and proposals to would always say, if you told him your equipment was designed to meet the requirements, "but will it work?" This catchphrase became a bit of a standing joke, but it's a very good question.

So Hitachi have some serious thinking to do about how they ended up here, and what they can do about it (if anything). On top of that, the single thing I imagine is causing the biggest concern in Hitachi Towers (legal division) is this:

Quote
134 During this investigation, the original 3D finite element model used to validate the performance of the IET design against the requirements of EN 15227 was modified extensively to better represent the design, and to match the actual collision?s consequences in terms of the derailment that consequently occurred (paragraph 94).

135 The results of the simulation for the design case from EN 15227 using the refined model are now different from what was reported to the Notified Body and Safety Authority during the original validation of the IET design.

Some of those changes to the model are not related to the derailment, but one aspect of its oversimplification was:

Quote
- The original model had taken advantage of the symmetry of the vehicle structure to model only one side of the vehicles. Symmetrical boundary conditions along the vehicle centreline had been created to represent the opposite side, but the effect of these was to prevent the model from moving laterally. This artificial mathematical limitation was removed by modelling both sides of the vehicle structure.

Of course there are those (Stadler, Alstom, etc.) who will be quick to point out that even moderately high-speed trains ought to be using Jacobs Bogies in any case. That keeps the carriage bodies firmly joined to each other, though it must remove the scope for absorbing crash energy outside those body shells.
« Last Edit: November 20, 2020, 09:48:21 am by stuving » Logged
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« Reply #26 on: November 20, 2020, 09:03:50 am »

So the answer was right, but the wrong question was asked? The apparent damage caused at such a low speed does serve to demonstrate to the layman the difference between speed and momentum, and the wisdom of having crumple zones. If I have correctly understood the full import of the parts of the report that you have drawn attention to, Stuving, will there have to be a much more detailed examination of the design of the IET, or even a reconsideration of how safe it is?
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« Reply #27 on: November 20, 2020, 12:34:16 pm »

What I hadn't realised was that the couplers have to collapse, and in most trains are designed to do so sacrificially (i.e. to protect the body shells). Hence in this case the RAIB identified that the failure of the couplers to collapse (shorten) was a primary cause of the derailment, and a design error. Exactly what should happen when the gap between the carriages has reduced to zero was not made clear (because it wasn't part of the accident). Presumably they should lock in some way, if only by being scrunched into each other.

I just wonder if the energy of the impact was below the give way point? There must be an engineering balance between being durable / reliable for every day duty and the point at which it needs to protect against impact.

Even at 15mph quite a bit of energy to redirect for a train that must be close on 300T for a 9 car hitting a stationary object
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« Reply #28 on: November 20, 2020, 02:50:14 pm »

Whilst the slow speed derailment should not have happened I think a more significant part of the summary is:

"The collision occurred because the driver of the Intercity Express Train was focused on reinstating an on-board system which he had recently isolated, instead of focusing on the driving task. This was exacerbated by him unintentionally commanding too much acceleration due to his lack of familiarity with the train.

The driver had isolated the on-board system at Leeds station because he had been unable to correctly set up the train management system. He had been unable to do this because ambiguous documentation from Hitachi, the train manufacturer, had led to LNER misunderstanding the required process for setting up the train management system when developing the content of its driver training programme.

The driver?s lack of adequate familiarity with the train probably arose because LNER had not recognised that his training needs were greater than for his peers."

The first paragraph seems to go against all principles of railway safety that a driver should be able to command a train to STOP (even if not in time) rather than abitarily automatically accelerate.

As a friend said do drivers have to computer "Geeks"


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« Reply #29 on: November 20, 2020, 04:36:14 pm »


The driver?s lack of adequate familiarity with the train probably arose because LNER had not recognised that his training needs were greater than for his peers."


Bit like on the GWR versions it was possible to when changing Pantograph ends to raise and hence the train VCB close while the other end was in the process of closing the earth switch on the lowering pantograph at the other end of the train, the trains have a 25kV bus from one end of a unit to the other.  couple of occasions of fire works in Paddington Stn
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