Croydon Tram Crash

[littlerock]

It looked to me, although difficult to see properly, that with the coach stabilised at an angle on its side with the lower end above ground, that an upper window panel had been opened or removed to allow passengers to escape. There was not much evidence of possessions on the ground or ripped off pieces of bodywork which suggests it remained pretty much intact.

 

[Peter Mugridge]

The crashed coach appears also to have landed on some vegetation rather than on a track with rails and ballast; that may well be a factor.

 

[rebmcr]

I believe earlier in the thread it was mentioned that Flexity vehicles might suffer from a design issue where the glass panels can detach from the frame more easily than desired.

I imagine the RAIB report will have to come out before that can be confirmed, but it could be a significant factor.

 

[MarlowDonkey]

Would a coach such as the one that crashed on the M40 have been fitted with seat belts? If in place and used, they could have protected the passengers from being thrown out if the coach overturned. Not that it would be practical to have seat belts on trams or trains.

 

[PermitToTravel]

Presumably the X90? Vehicles on that route have seat belts.

 

[AlterEgo]

A bus overturned in fog on the M40 last night and went onto the grassy verge. There were 17 injuries but no fatalities. Trams are supposedly built to the same safety standards and yet the Croydon crash was much more serious. I am posting a link here to the Daily Mail coverage which has a lot of photos. The bus's windows do not appear to be broken. I realise the bus would have been going more slowly than the tram but is this the whole story? Did the bus have stronger windows? Interested in your views.

http://www.dailymail.co.uk/news/art...e-grip-UK-weather-warnings-place-country.html

How can you tell from that article? The main pictures show the bus on its side and no windows are visible. A further picture and the video show the bus' left hand side completely devoid of window glass - perhaps removed by rescuers. How do you know none of the windows were broken? Am I missing something?

 

[AlterEgo]

Presumably the X90? Vehicles on that route have seat belts.

And no standees.

 

[Bletchleyite]

Presumably the X90? Vehicles on that route have seat belts.

Though I would estimate compliance as well under 50%.

Coaches, however, have double glazed windows...


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[daikilo]

Coaches, however, have double glazed windows...

Double glazing in itself does not help, laminated glass does as it holds particles to the plastic layer.

If all the windows on the left side have gone then I am puzzled.

 

[Taunton]

And no standees.

And no groups standing by the entrance doors, which unlike the rest of the structure offer no resistance to being ripped off when sliding. Nor providing seats for only one-third of the passenger capacity.

 

[Shimbleshanks]

Presumably the X90? Vehicles on that route have seat belts.

In my experience, rate of seat-belt wearing on scheduled coach services is very low, even where they are provided.
CL

 

[button_boxer]

Presumably the X90? Vehicles on that route have seat belts.

News reports say it was a service from Heathrow Airport so that would be an "airline" service rather than X90.

 

[bramling]

The crashed coach appears also to have landed on some vegetation rather than on a track with rails and ballast; that may well be a factor.

It's also worth adding that having watched a training video of the Sandilands curve, at the time that was filmed the cess area where the tram derailed was being used for storage of spare rails and some other track components. Needless to say it doesn't necessarily follow that this was the case on the day of the derailment.

OHLE components can also do quite a bit of damage when a derailed vehicle strikes them. Hatfield and Potters Bar are both examples of this.

 

[neonison]

A further interim report has been published.
https://assets.publishing.service.g...500001c/IR012017_170220_Sandilands_Jn_IR2.pdf

 

[Tetchytyke]

A further interim report has been published.
https://assets.publishing.service.g...500001c/IR012017_170220_Sandilands_Jn_IR2.pdf

Interesting report.

I'm astounded there was no stepped speed restriction on the approach to that corner, as there generally is on the Metro system up here.

Interesting interim conclusions too.

 

[littlerock]

So the people killed were thrown out of the windows? I still think this validates my point for needing stronger glass in the windows.

Also the report says the driver "lost awareness" shortly before the accident and did not fully brake in time. It leaves unclear why he lost awareness, maybe fell asleep. But can anyone do the maths and tell me if he should already have been travelling more slowly and breaking harder, before the point at which he officially "lost awareness".

 

[Tetchytyke]

Also the report says the driver "lost awareness" shortly before the accident and did not fully brake in time. It leaves unclear why he lost awareness, maybe fell asleep.

The report highlighted that, by the time a driver could see the speed restriction sign, it was already too late to brake the train sufficiently to get the train down to the correct speed. He should have been braking long before he started to. The report says braking should start about 180m from the corner, but the sign only became visible at 60m on dipped headlights in that weather. The driver was braking for about 2.5s, which at that speed equals about 55m.

I'm going to hypothesise that he lost situational awareness, saw the speed restriction sign and applied full service brake. But it was way too late by then.

 

[rebmcr]

Also the report says the driver "lost awareness" shortly before the accident

The report DOES NOT say that, it is a suggested possible explanation.

and did not fully brake in time. It leaves unclear why he lost awareness, maybe fell asleep. But can anyone do the maths and tell me if he should already have been travelling more slowly and breaking harder, before the point at which he officially "lost awareness".

It states that route knowledge should be used by all drivers to reduce speed in preparation for the 20kmh restriction.

The suggested explanation would seem to be a case of the driver believing the tram was further away from the curve than it actually was -- so IF THAT IS TRUE, it would mean that the 'loss of awareness' spanned from a unknown point where the location was first misinterpreted, until the brake application.

 

[WatcherZero]

Report also says the Driver failed to activate the emergency brakes which they are saying is another sign that they lost attention. The speed sign should have been at least twice as far from the curve to be effective.

The Tram structure and fittings did not deform in the impact and passengers inside were mostly unhurt. The failure was the windows (6mm toughened glass with 4mm toughened glass on doors and an anti-vandal coating) which seems to have accounted for nearly 100% of the fatalities/serious injuries.

 

[Taunton]

Report says very little new that the last one didn't. Mostly padding.

The issue of the advance speed sign fails to mention that there are only a very few advance speed signs on any railway (or tramway), the vast majority are just signed at point of commencement, and always have been. They are regarded as more of a marker than a safety command to drivers - they are not illuminated at night.

And this approach of course has been accepted by generations of government Inspecting Officers.

 

[rebmcr]

Report says very little new that the last one didn't. Mostly padding.

The issue of the advance speed sign fails to mention that there are only a very few advance speed signs on any railway (or tramway), the vast majority are just signed at point of commencement, and always have been. They are regarded as more of a marker than a safety command to drivers - they are not illuminated at night.

And this approach of course has been accepted by generations of government Inspecting Officers.

On the mainline railway, at least before TPWS was implemented, this sort of significant reduction would be preceded by an AWS warning. Perhaps advance warning signs should be more appropriate on segregated tramways than on other systems.

 

[Tetchytyke]

The issue of the advance speed sign fails to mention that there are only a very few advance speed signs on any railway (or tramway), the vast majority are just signed at point of commencement, and always have been. They are regarded as more of a marker than a safety command to drivers - they are not illuminated at night.

I think relying on a driver's memory and situational awareness is always going to be the weak link of this sort of system, especially on tramways and light railways which don't have the same sorts of train protection systems.

Where you get dramatic changes in speed limit you do normally see some advance warning signs, in the triangle signs. This is especially the case where there is a particularly sharp drop in speed limit or a particularly low limit, which a limit of 20km/h definitely is.

I'm surprised a change from 80km/h to 20km/h was not reduced in stages. I wouldn't be surprised to see that as a RAIB recommendation, regardless of why the driver lost situational awareness.

 

[Taunton]

Perhaps advance warning signs should be more appropriate on segregated tramways than on other systems.

It is true that this section had far more of a railway than tramway characteristic - separate alignment, high speed, etc - in fact it is of course a former railway alignment (up to the sharp tram-style curve). But because tram vehicles use it then it got categorised as such. Bit of a hole in the logic.

 

[theageofthetra]

On the mainline railway, at least before TPWS was implemented, this sort of significant reduction would be preceded by an AWS warning. Perhaps advance warning signs should be more appropriate on segregated tramways than on other systems.

Can think of several examples on the routes I sign where no AWS warning exists despite a significant speed reduction. There are a few on the Hayes branch including the 60 to 20 PSR on the up at the very sharp curve approaching Elmers End- which must be one of tightest radius curves on the rail network.

 

[daikilo]

Had this been a road, I would imagine for such a drop in speed, there would be an advanced warning of both the upcoming bend and the speed limit with probably a distance indication (say at 200m). There may be a flashing amber light above the sign.

Between that point and the bend there would possibly be the 3/2/1 striped marker boards and possibly rumble strips on the road surface as well as words such as slow.

Just before the bend there would also be a bend sign with the speed limit and probably the word danger somewhere.

On the outside of the bend there would probably be a series of arrow boards possibly with flashing amber lights.

The reason I have listed this is that had this been a bus on a road there would probably be a series of cues for the driver, when in this case there was only one and far too late. The analogy between a bus and a tram rather than a train and a tram is thus invalid, a tram is (sometiles) in a world of its own.

 

[Western Lord]

Had this been a road, I would imagine for such a drop in speed, there would be an advanced warning of both the upcoming bend and the speed limit with probably a distance indication (say at 200m). There may be a flashing amber light above the sign.

Between that point and the bend there would possibly be the 3/2/1 striped marker boards and possibly rumble strips on the road surface as well as words such as slow.

Just before the bend there would also be a bend sign with the speed limit and probably the word danger somewhere.

On the outside of the bend there would probably be a series of arrow boards possibly with flashing amber lights.

The reason I have listed this is that had this been a bus on a road there would probably be a series of cues for the driver, when in this case there was only one and far too late. The analogy between a bus and a tram rather than a train and a tram is thus invalid, a tram is (sometiles) in a world of its own.

Roads do not have speed limit reductions for bends. There may be an advisory speed sign, but I cannot think of any example of the legal limit being reduced for a bend. Country lanes with the national speed limit of 60mph would be festooned with them if there were. It is left to the driver's judgement to slow to an appropriate speed.

 

[neonison]

There are some mandatory speed limits at certain bends on the UK road network such as Bredbury on the M60 and on the A102(M) last time I was down that way. Rare, yes, unknown, no.

 

[jon0844]

The M11 has, or had, some lower speed limits in certain sections. As does the M4 in London. And on rural roads, it's quite common to stagger limits from 60 or 70 to 30, with a short section of 40.

 

[rebmcr]

Although roads are line of sight (like trams); they are not based on route knowledge (unlike trams).

Trams are not directly comparable to roads nor mainline rail.

 

[WatcherZero]

I'm surprised a change from 80km/h to 20km/h was not reduced in stages. I wouldn't be surprised to see that as a RAIB recommendation, regardless of why the driver lost situational awareness.

It is, they are recommending that transition greater than 30kph between signs have intermediary signs.