UK train crash

[caravanman]

link

 

[George Harris]

Update 11:39am GMT: 1 killed

www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/02/24/ncrash324.xml

From the same newspaper.

Nine carriages on their side and down an embankment.

"There were about 180 passengers on the 5.15pm from Euston to Glasgow Central — a Virgin "Pendolino" tilting train — which derailed in the mountainous area between Kendal and Penrith at about 8.16pm.

Virgin boss Sir Richard Branson arrived at the scene of the accident after visiting casualties in hospital today.

Sir Richard stressed the safety features of the Pendolino and said he feared the accident could have been much worse if it had involved an old train."

>>> That last I consider self-serving nonsense<<<<

"Power lines were dragged down, making it difficult for rescuers to reach casualties. An ambulance spokesman said: "We have reports of various injuries, from leg injuries to back injuries and head injuries — ranging from minor to quite serious."

It was unclear how fast the train was going or what caused it to derail. But Pendolinos are the fastest domestic trains operating in Britain.

A Network Rail spokesman at Glasgow Central station said the line speed for the area was 95mph.

About 40 people escaped quickly, as three RAF Sea King helicopters were scrambled to the scene alongside ambulances from the nearest hospital, which is 90 minutes away. Dumfries Royal Infirmary was on standby as mountain rescue teams sped to the relatively inaccessible region between Oxenholme and Tebay."

 

[jeriwho]

What makes a train derail?

I have noticed that passenger car derailments are rare, but over the last couple months here in the USA there have been several freight train derailments.

What makes a train derail? And why do freight cars derail more often than passenger trains? Does anybody know?

Thanks for any info!

jeriwho

 

[AmtrakWPK]

I would guess there are perhaps 5,000 to 50,000 (or more) freight cars in use on the rail systems in this country for each single rail passenger car. And a loaded freight car (a car loaded with coal, for instance, or scrap steel), makes a passenger car look like a feather, weight-wise.

 

[Sam Damon]

Ahh, yes.

Some more grist for the "are the USA railroad passenger crash standards too high" mill. It will be interesting to see some pictures from this wreck.

Speaking of which, the BBC website has a photo essay.

 

[Sam Damon]

At the above link, the caption for picture #10 paraphrases Sir Richard Branson this way: "The Virgin boss said despite the force of the impact no windows were broken and the carriages did not crumple."

The photo essay also asserts that investigators are looking at a switch as the cause of the derailment.

 

[Brian UK]

Ahh, yes.
Some more grist for the "are the USA railroad passenger crash standards too high" mill. It will be interesting to see some pictures from this wreck.

BBC news is a good place to start http://news.bbc.co.uk/1/hi/uk/6392197.stm

As usual, the ill-informed and uneducated are getting into a frenzy about rail safety - read some of the comments posted - and calling for all manner of actions to be taken, including fitting of seatbelts (!), speed reductions and generally over-reacting to what is a tragic but rare event. Union leaders are also spouting politically motivated nonsense to suit their own agenda. All this is before the cause has been identified, though current speculation is a faulty set of facing points (switches).

 

[jamesontheroad]

This graphic from the BBC explains what is believed to have happened. From a story on this page

*j*

 

[jeriwho]

I would guess there are perhaps 5,000 to 50,000 (or more) freight cars in use on the rail systems in this country for each single rail passenger car. And a loaded freight car (a car loaded with coal, for instance, or scrap steel), makes a passenger car look like a feather, weight-wise.

But wouldn't more weight make a car LESS likely to topple over? I was wondering if friction from a train distorts the rails (?) so thast over time the rails themselves become less stable.

Anyway, I regret that the crash has become a political football (but I cannot see the flaw in suggesting seatbelts for trains), but I hope somebody can explain the mechanics of derailment.

Thanks for any additional info!

jeriwho

 

[AlanB]

But wouldn't more weight make a car LESS likely to topple over? I was wondering if friction from a train distorts the rails (?) so thast over time the rails themselves become less stable.
Anyway, I regret that the crash has become a political football (but I cannot see the flaw in suggesting seatbelts for trains), but I hope somebody can explain the mechanics of derailment.

Thanks for any additional info!

jeriwho

If the weight is at the bottom of the car, then yes it would be a little less likely to topple over. But even then, enough force in the right spot, along with a steep slope next to the track and anything will topple over. In most cases however, that extra weight is distributed throughout the car. And of course too much weight at the top would make it more likely to topple over.

As for what can cause derailments, there are several leading causes. A collision with something else on the tracks, like a big boulder that rolled down a mountain, another train, a car or a truck on the tracks. A problem with a switch, which is what the preliminary reports seen to suggest caused the crash above. A worn rail that breaks. A sun kink.

When it comes to switches, many things can go wrong there. Misalignment, a switch that moves after part of the train has already passed over it, worn points which fail to direct all the wheels in the correct direction. Any of those can simply force the wheels off the tracks completely on their own, or they can cause part of the train to go down one track, while the rest tries to go down the other track.

Worn rails, which you alluded to, usually end up causing the rails to break. They can break cleanly and then become misaligned, so that it's no longer a continuous rail. Or the top (flatter and wider part of the rail) of the rail can break off. That can then cause the wheels to fall off the rails.

Sun kinks are a more modern problem, in this era where we weld rail sections together, instead of just bolting them together. It was the gaps between bolted sections that cause the infamous clickity clack of the train world. With welded rail you don't have a gap, sometimes for thousands of feet. As the rail heats up during the summer months, it like most things expands. If the rail expands too much and other factors like poor ballast, poor anchors, come into play, the rail can bow out. If that happens, the rail is now too wide for the fixed width between the rails and the train falls off the rails and derails.

There are probably a few other things that can cause problems, and some of the above is an over simplification of things, but it should give you a good idea into some of the causes for derailments.

 

[jeriwho]

If the weight is at the bottom of the car, then yes it would be a little less likely to topple over. But even then, enough force in the right spot, along with a steep slope next to the track and anything will topple over. In most cases however, that extra weight is distributed throughout the car. And of course too much weight at the top would make it more likely to topple over.
As for what can cause derailments, there are several leading causes. A collision with something else on the tracks, like a big boulder that rolled down a mountain, another train, a car or a truck on the tracks. A problem with a switch, which is what the preliminary reports seen to suggest caused the crash above. A worn rail that breaks. A sun kink.

When it comes to switches, many things can go wrong there. Misalignment, a switch that moves after part of the train has already passed over it, worn points which fail to direct all the wheels in the correct direction. Any of those can simply force the wheels off the tracks completely on their own, or they can cause part of the train to go down one track, while the rest tries to go down the other track.

Worn rails, which you alluded to, usually end up causing the rails to break. They can break cleanly and then become misaligned, so that it's no longer a continuous rail. Or the top (flatter and wider part of the rail) of the rail can break off. That can then cause the wheels to fall off the rails.

Sun kinks are a more modern problem, in this era where we weld rail sections together, instead of just bolting them together. It was the gaps between bolted sections that cause the infamous clickity clack of the train world. With welded rail you don't have a gap, sometimes for thousands of feet. As the rail heats up during the summer months, it like most things expands. If the rail expands too much and other factors like poor ballast, poor anchors, come into play, the rail can bow out. If that happens, the rail is now too wide for the fixed width between the rails and the train falls off the rails and derails.

There are probably a few other things that can cause problems, and some of the above is an over simplification of things, but it should give you a good idea into some of the causes for derailments.

Thanks Alan! That was a great explanation.

jeriwho