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Comment by direwolf20 | Hacker News Reader

TFA indicates a 40cm gap — huge!

I suppose that counts/was caused by a fracture but almost a half meter of gap in the track is nuts. Like describing a limb that’s totally removed as a bone fracture.

Though conceivably the break was very small and a train impacting the slightly lifted rail just caused a good chunk of it to explode.

> Though conceivably the break was very small and a train impacting the slightly lifted rail just caused a good chunk of it to explode.

The crown (top) of the rail seems to be missing after the gap. The crown-less section then continues ~3 meters before it disappears behind the investigator on the left. IDK what that might indicate.

ref pic: https://ichef.bbci.co.uk/news/1024/cpsprodpb/ecb4/live/53924...

The rail is laying on its side in that picture, so what is visible is the foot not the web.

edit: other angles of the same location here: https://youtu.be/DIQ4SrGSua0?t=1174

> The rail is laying on its side in that picture

Ah, I see it now. The marks from contact with the ties should have clued me in earlier.

Yes, the “fracture” (the problem was actually at a joint) was there for a while. The missing segment of rail was still there when the train arrived - the derailment affected only the last cars.

The "fracture" being referred to is a weld that somehow failed. The gap you are seeing is because an enormous, heavy train travelling at 200km/h hit that fracture and the rear half of the train derailed, tearing up sleepers and kicking all manner of debris around including ballast and, in this case, parts of newly-fractured (and therefore weakened) track.

No, that gap was created after the rail broke and the train derailed as a result.

The crack was in the weld, causing one side to sink and the wheel to hit the start of the next section of rail which was no longer welded to it, causing stress fractures to form in the rail which later caused that 40cm piece to break off.

Next to the weld, if we're being pedantic. The weld itself is stronger than regular rail, but the welding process weakens the rail right next to it.

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