Croydon Tram Crash

[jon0844]

I take it you don't drive in certain parts of Hertfordshire at certain times? If you did you would find that *every* route is jammed to at least some extent. Too many people and not enough space in certain parts of the country.

Correct, there are some no go areas at certain times. I can't literally avoid every jam but I can avoid things that are out of the ordinary.

And I know that if I'm one day being told to go some crazy route, I follow it (subject to usual rules, like not going off a cliff or onto a railway line...!).

 

[vrbarreto]

Caught the tram today... As busy as usual.. Didn't feel unsafe..

There are big notices in the trams though asking people to phone or email if they see something they feel is affecting safety...

 

[urpert]

Again, this tram just as busy as it's always been. I couldn't spot any different signage or 'beacons', though we did seem to take the Harrington Rd curve even slower than usual.

Incidentally, what a terrible ride the Stadlers have.

 

[amcluesent]

Did they die needlessly due to design bungles?

Controversial glass may have been the cause of more fatalities in the Croydon Tram Crash, according to investigators.

The Rail Accident Investigation Branch (RAIB), one of several agencies investigating the cause of the disaster, is thought to be exploring whether lives could have been saved if the tram had been fitted with shatterproof safety glass.

http://www.dailymail.co.uk/news/art...sh-victims-saved-tram-shatterproof-glass.html

 

[Domh245]

Possibly, and it was discussed in some depth on here, but having seen this picture, I wouldn't be surprised to learn that those who lost their lives were stood in the doorways.

 

[507 001]

Possibly, and it was discussed in some depth on here, but having seen this picture, I wouldn't be surprised to learn that those who lost their lives were stood in the doorways.

I've been saying for a while that there is too much glass in those doors......

 

[Domh245]

I've been saying for a while that there is too much glass in those doors......

My concern was more with the fact that one of the door leaves has come off entirely. It could have been a more robust frame/mechanism instead, but then you start to have to weigh up the need for rapid door cycle times with the unlikely event of a crash severe enough to rip the door apart

(Unless of course that LHS leaf was cut off as part of the rescue attempt? It does seem a bit odd for one frame to come off and the other remain largely intact)

 

[Bletchleyite]

I've been saying for a while that there is too much glass in those doors......

Glass is absolutely fine if it is laminated *and* double glazed. A brick often bounces off double-glazing.

 

[WatcherZero]

They likely came across the same design dilemma as buses, you can make the glass tougher but then you face the issue in an accident that emergency services cannot then easily break it to rescue passengers and if theres a fire more are likely to die because they have less escape routes. on buses there is usually intentionally one weak pane of glass. Weve gone beyond the days of the emergency hammer though as even weak glass would be too strong for a little toffee hammer to break.

 

[Bletchleyite]

Fires in train crashes are quite rare - particularly electric ones. And emergency services can cut a vehicle open if they need to.


Sent from my iPad using Tapatalk

 

[flymo]

on buses there is usually intentionally one weak pane of glass. Weve gone beyond the days of the emergency hammer though as even weak glass would be too strong for a little toffee hammer to break.

Nope. All bus windows except the front ones are toughened glass to the same standard. All windows (except the front ones) can be broken with the emergency hammer or any firm blow and then pushed out, as they shatter into a thousand pieces.

 

[Taunton]

In rail vehicle design we have progressively over time made the vehicle structure stronger and more able to withstand collision/overturning forces.

However, we have ignored that along with this, there has been a commercial desire to provide an ever-reducing proportion of seats, making an ever larger proportion of passengers stand (because you can then pack more passengers in per vehicle). Nobody ever seems to do any risk assessment of this approach (the London Underground S-stock replacing the A-stock with only around half the number of seats, but a greater overall capacity, being a classic example). Where do most passengers tend to stand? Around the doors. Where is the weak point in structural strength and inability to retain passengers safely within the vehicle? Around the doors.

 

[Robertj21a]

They likely came across the same design dilemma as buses, you can make the glass tougher but then you face the issue in an accident that emergency services cannot then easily break it to rescue passengers and if theres a fire more are likely to die because they have less escape routes. on buses there is usually intentionally one weak pane of glass. Weve gone beyond the days of the emergency hammer though as even weak glass would be too strong for a little toffee hammer to break.

Surely, these trams have doors on both sides - so it's less likely they'll need to break the glass to effect any rescue.

 

[Simon11]

In rail vehicle design we have progressively over time made the vehicle structure stronger and more able to withstand collision/overturning forces.

However, we have ignored that along with this, there has been a commercial desire to provide an ever-reducing proportion of seats, making an ever larger proportion of passengers stand (because you can then pack more passengers in per vehicle). Nobody ever seems to do any risk assessment of this approach (the London Underground S-stock replacing the A-stock with only around half the number of seats, but a greater overall capacity, being a classic example). Where do most passengers tend to stand? Around the doors. Where is the weak point in structural strength and inability to retain passengers safely within the vehicle? Around the doors.

I don't see the need for this. Compare the safety records of travelling by tube compared to car and there are far bigger hazards and risk out there.

 

[AlterEgo]

I don't see the need for this. Compare the safety records of travelling by tube compared to car and there are far bigger hazards and risk out there.

True, but the appetite for risk on public transport is much, much smaller than private transport.

 

[edwin_m]

They likely came across the same design dilemma as buses, you can make the glass tougher but then you face the issue in an accident that emergency services cannot then easily break it to rescue passengers and if theres a fire more are likely to die because they have less escape routes. on buses there is usually intentionally one weak pane of glass. Weve gone beyond the days of the emergency hammer though as even weak glass would be too strong for a little toffee hammer to break.

RSSB sponsored some research into types of glass, which concluded that laminated glass should be adopted because it is better at keeping passengers inside the train in an accident. In the same report the emergency services confirmed that laminated rather than toughened glass would make no difference to their ability to evacuate passengers from an overturned vehicle. Hence is is now recommended that all train windows should be laminated, though this hasn't been applied to the whole fleet as yet.

On a train there are very few situations where speedy self-evacuation will save lives, and some where it could make things worse. For example people may get out and be hit by trains that have not yet been stopped on adjacent lines, as happened with the Maidenhead HST fire some years ago. The hammers also create other hazards, so are likely to disappear in time. That particular situation doesn't apply to trams, but I would expect the balance of risk still to favour laminated glass.

 

[PermitToTravel]

True, but the appetite for risk on public transport is much, much smaller than private transport.

Although it doesn't change the fact that money spent on improvements to the crashworthiness of railway vehicles, particularly mid-life, will save considerably more lives if it's just spent on motoring prosecutions.

 

[littlerock]

Judging from reports of motorway coach crashes in the past, where the coach overturned (eg Heathrow NE crash 2007), serious injury occurs most often where the window glass shatters and passengers not wearing seatbelts are thrown out or dragged along the ground inside the coach. At least on motorway buses passengers are seated and should be wearing seat belts.

There is no such requirement on trams where indeed sitting may not be possible. And on a tram travelling on rail tracks relatively high speeds are achievable. So should they be subject to the same safety code as urban buses or something stringent in particular regarding the windows?

I honestly think the perceived need for "escape glass" and hammers is a red herring. The RSSB did extensive surveys, as reported above, and found the occasions when smashing the glass to escape were needed, were vanishingly few, if at all. By contrast many more fatalities and serious injuries were caused, as at Croydon, by people being thrown out of coaches which overturned and threw people out of the window or dragged them along the ground inside it after it overturned and broke the windows. This is why reinforced windows were introduced.
--- old post above --- --- new post below ---
Judging from reports of motorway coach crashes in the past, where the coach overturned (eg Heathrow NE crash 2007), serious injury occurs most often where the window glass shatters and passengers not wearing seatbelts are thrown out or dragged along the ground inside the coach. At least on motorway buses passengers are seated and should be wearing seat belts.

There is no such requirement on trams where indeed sitting may not be possible. And on a tram travelling on rail tracks relatively high speeds are available. So should they be subject to the same safety code as urban buses?

I honestly think the perceived need for "escape glass" and hammers is a red herring. The RSSB did extensive surveys, as reported above, and found the occasions when smashing the glass to escape were needed, were vanishingly few, if at all. By contrast many more fatalities and serious injuries were caused, as at Croydon, by people being thrown out of buses or coaches which overturned and threw people out of the window or dragged them along the ground inside it after it overturned and broke the windows.

 

[edwin_m]

Judging from reports of motorway coach crashes in the past, where the coach overturned (eg Heathrow NE crash 2007), serious injury occurs most often where the window glass shatters and passengers not wearing seatbelts are thrown out or dragged along the ground inside the coach. At least on motorway buses passengers are seated and should be wearing seat belts.

There is no such requirement on trams where indeed sitting may not be possible. And on a tram travelling on rail tracks relatively high speeds are achievable. So should they be subject to the same safety code as urban buses or something stringent in particular regarding the windows?

I honestly think the perceived need for "escape glass" and hammers is a red herring. The RSSB did extensive surveys, as reported above, and found the occasions when smashing the glass to escape were needed, were vanishingly few, if at all. By contrast many more fatalities and serious injuries were caused, as at Croydon, by people being thrown out of coaches which overturned and threw people out of the window or dragged them along the ground inside it after it overturned and broke the windows. This is why reinforced windows were introduced.

I largely agree with this, although your post suggests that motorway coaches that operate faster than trams aren't fitted with laminated glass. Does anyone know what standards, if any, apply to the windows of either express coaches or urban buses?

 

[PermitToTravel]

I'm not sure about standards, but they're pretty much always just toughened glass. Removable hammers are slowly disappearing and being replaced with buttons on the surface of the glass that can be hit to smash through.

The front downstairs windscreen has some containment function. Are upstairs windscreens laminated?

 

[edwin_m]

The front downstairs windscreen has some containment function. Are upstairs windscreens laminated?

I don't know but I would hope so. Unlike the driver downstairs the passengers in the front seats on top don't have seat belts, and a sudden stop could throw them forwards into the windscreen. Particularly hazardous on some newer designs where its bottom edge is lower than on older vehicles.

 

[littlerock]

I read that trams and urban buses have tempered glass windows (I think this is the kind that disintegrates into thousands of tiny squares?) although the driver's cab window, on a tram or light railway, is of laminated glass. Anyone able to confirm?

 

[flymo]

I read that trams and urban buses have tempered glass windows (I think this is the kind that disintegrates into thousands of tiny squares?) although the driver's cab window, on a tram or light railway, is of laminated glass. Anyone able to confirm?

On buses windscreens are laminated, the rest are not. All glass must be safety glass, whether that is toughened or laminated.

 

[61653 HTAFC]

The issue with the doors does make me wonder how a pacer would behave in the event of overturning. The bus doors seem as if they'd come apart fairly easily, and if heavily loaded the likelihood of passengers being ejected seems quite high.

 

[Bletchleyite]

The issue with the doors does make me wonder how a pacer would behave in the event of overturning. The bus doors seem as if they'd come apart fairly easily, and if heavily loaded the likelihood of passengers being ejected seems quite high.

The saloon windows are single-glazed anyway so would probably be just as vulnerable.

 

[BestWestern]

The issue with the doors does make me wonder how a pacer would behave in the event of overturning. The bus doors seem as if they'd come apart fairly easily, and if heavily loaded the likelihood of passengers being ejected seems quite high.

The doors on a Pacer are held closed by 'waist locks', a sort of latch that mechanically holds the doors in the closed position. Next time you're on one have a look. Although the doors are of bus origin, that is a significant feature not found on buses, where the doors are held closed by air pressure alone.

 

[edwin_m]

The doors on a Pacer are held closed by 'waist locks', a sort of latch that mechanically holds the doors in the closed position. Next time you're on one have a look. Although the doors are of bus origin, that is a significant feature not found on buses, where the doors are held closed by air pressure alone.

Most of the door is glass so if that breaks the question of whether the frame is still held in place isn't really relevant. However Pacer doors are also recessed so it may be that in an overturning the rest of the bodyside would protect the doors. On the other hand, recent Underground stock has doors on external runners and it looks like those would be torn off immediately should the train overturn. But the very fact all these trains have been in service for many years without this happening shows how rare an event it is.

 

[big_dirt]

The doors on a Pacer are held closed by 'waist locks', a sort of latch that mechanically holds the doors in the closed position. Next time you're on one have a look. Although the doors are of bus origin, that is a significant feature not found on buses, where the doors are held closed by air pressure alone.

Is it not that the doors are naturally closed and the air pressure pushes them open, meaning that the default position is closed when air pressure is lost?

 

[Bletchleyite]

Is it not that the doors are naturally closed and the air pressure pushes them open, meaning that the default position is closed when air pressure is lost?

No. Like bus doors, without air pressure they don't default to anything, they can be easily pushed in either direction. The locks are electrically operated, though, so can be set or released without air pressure. (I've boarded a Pacer at a terminus station which had no air pressure left - the door button undid the lock with an audible clunk but it was necessary to push the door manually, and once pushed it stayed where it had been pushed to).

FWIW, most German buses have this kind of lock as well, on Citaros for example you have to turn a knob on the door to release it in emergency. I believe it's not allowed in the UK.
--- old post above --- --- new post below ---

Most of the door is glass so if that breaks the question of whether the frame is still held in place isn't really relevant. However Pacer doors are also recessed so it may be that in an overturning the rest of the bodyside would protect the doors. On the other hand, recent Underground stock has doors on external runners and it looks like those would be torn off immediately should the train overturn. But the very fact all these trains have been in service for many years without this happening shows how rare an event it is.

The vast majority of the time it isn't really possible for a Tube train to overturn anyway, as the narrow tunnel would hold it upright. For it to spin on its centre axis would be very difficult indeed - way too much friction.

Would be technically possible above ground, but they still have very low centres of gravity. Or I suppose the SSL would be as vulnerable as the mainline as it's basically mainline stock.

 

[edwin_m]

The vast majority of the time it isn't really possible for a Tube train to overturn anyway, as the narrow tunnel would hold it upright. For it to spin on its centre axis would be very difficult indeed - way too much friction.

Would be technically possible above ground, but they still have very low centres of gravity. Or I suppose the SSL would be as vulnerable as the mainline as it's basically mainline stock.

I was thinking more of S Stock, although the original Metrolink trams had a similar vulnerability. However, a Tube train derailing and scraping the side of the tunnel could also lose its doors and this would also be a hazard particularly if it was crush-loaded.