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If you run a high speed train over a ballasted track the under carriage aerodynamics suck the ballast up and they can hit the bogeys and axles and cause cracks
by kingkongjaffa 3y ago
If you run a high speed train over a ballasted track the under carriage aerodynamics suck the ballast up and they can hit the bogeys and axles and cause cracks in the train axle. If this happens in a bad way it can derail the train.
This abstract has a good summary https://research.birmingham.ac.uk/en/publications/a-full-scale-experimental-and-modelling-study-of-ballast-flight-u https://research.birmingham.ac.uk/en/publications/a-full-sca...
So the question becomes can we replace ballast with some other mechanism where this doesn’t happen?
- luplex 3y agoWe can and do for many new high-speed rail developments: https://en.m.wikipedia.org/wiki/Ballastless_track https://en.m.wikipedia.org/wiki/Ballastless_track It's more expensive to build and fix, but it's also more reliable and needs less maintenance.
- seszett 3y agoI'm pretty sure TGV tracks do use ballast though, don't they? And they are among the fastest trains in operation, so it seems to work fine for them.
- kingkongjaffa 3y agoYeah the occurrence is fairly rare which is why we don’t do much about it. And we trust that NDT(non destructive testing) like die and ultrasonic etc, periodic testing will catch any cracks.
- willyt 3y agoHere’s a TGV speed test on a ballasted track. There’s an axle cam and it doesn’t look like there’s big chunks flying about but it does stir up a lot of dust at 575km/h (~360mph) https://m.youtube.com/watch?v=EOdATLzRGHc&t=11s&pp=ygURdGd2IHNwZWVkIHJlY29yZCA%3D https://m.youtube.com/watch?v=EOdATLzRGHc&t=11s&pp=ygURdGd2I...