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The author keeps asserting the "inherent weakness" of steel-on-steel railways; however, there are very good reasons it has been settled on as a good choice. Fri

The author keeps asserting the "inherent weakness" of steel-on-steel railways; however, there are very good reasons it has been settled on as a good choice. Friction and sound losses are generally minimized, thanks to a very small contact surface and smooth, hard materials with little give; wheels can be re-machined back into spec a couple times rather than being replaced; rails can be re-used for lower-speed applications when worn; unlike pneumatic tires, steel can be machine into conical, self-centering, turn-adapting geometries with fixed axles and no need for differentials; the list continues and is quite long. Apparently, a recent change to wheel geometry reduced wear and extended lifetime by as much as 40%. See Practical Engineering's latest video: https://www.youtube.com/watch?v=Nteyw40i9So https://www.youtube.com/watch?v=Nteyw40i9So

ianbicking 3y ago
Makes a lot of sense for freight... lots of weight, most miles going through lower population areas. Feels a little silly for relatively light humans being transported through high population areas.
- singleshot_ 3y ago
  Check out people movers at large airports: they look like trains, run on their own tracks, but have tires.
- TylerE 3y ago
  The humans may be light... the car around them built to survive a 100mph crash certainly isn't.
  - user_7832 3y ago
    Sure but buses and cars themselves are strong enough and use rubber tyres. Not that I think rubber's a good idea for trains, but still.
    - TylerE 3y ago
      You really don't want to see what a 90mph crash in a bus looks like. It ain't pretty. Those speeds are unreasonable for a bus, but common on commuter rail in many civilized places.
    - woodpanel 3y ago
      > strong enough no car or bus survives a 150 km/h crash
  - ianbicking 3y ago
    Imagine what airplanes would look like if we wanted to build them to survive a crash... I'm also a little unclear how humans could survive a 100mph crash even if their container makes it through. If they were wearing a 4-point harness, I guess? Do they build crumple zones into train cars? Or... just rely on utterly demolishing anything they hit so the deceleration is kept under control? (https://www.reddit.com/r/BitchImATrain/ https://www.reddit.com/r/BitchImATrain/) Some nice analysis of survivable deceleration here (with restraints): https://aviation.stackexchange.com/questions/16545/even-after-years-of-research-why-are-planes-unable-to-keep-passengers-alive-in https://aviation.stackexchange.com/questions/16545/even-afte... (100mph=44m/s)
hyperthesis 3y ago
Feynman on the turn-adapting bit https://youtube.com/watch?v=y7h4OtFDnYE https://youtube.com/watch?v=y7h4OtFDnYE

ianbicking 3y ago

Makes a lot of sense for freight... lots of weight, most miles going through lower population areas. Feels a little silly for relatively light humans being transported through high population areas.

singleshot_ 3y ago
Check out people movers at large airports: they look like trains, run on their own tracks, but have tires.
TylerE 3y ago
The humans may be light... the car around them built to survive a 100mph crash certainly isn't.
- user_7832 3y ago
  Sure but buses and cars themselves are strong enough and use rubber tyres. Not that I think rubber's a good idea for trains, but still.
  - TylerE 3y ago
    You really don't want to see what a 90mph crash in a bus looks like. It ain't pretty. Those speeds are unreasonable for a bus, but common on commuter rail in many civilized places.
  - woodpanel 3y ago
    > strong enough no car or bus survives a 150 km/h crash
- ianbicking 3y ago
  Imagine what airplanes would look like if we wanted to build them to survive a crash... I'm also a little unclear how humans could survive a 100mph crash even if their container makes it through. If they were wearing a 4-point harness, I guess? Do they build crumple zones into train cars? Or... just rely on utterly demolishing anything they hit so the deceleration is kept under control? (https://www.reddit.com/r/BitchImATrain/ https://www.reddit.com/r/BitchImATrain/) Some nice analysis of survivable deceleration here (with restraints): https://aviation.stackexchange.com/questions/16545/even-after-years-of-research-why-are-planes-unable-to-keep-passengers-alive-in https://aviation.stackexchange.com/questions/16545/even-afte... (100mph=44m/s)

hyperthesis 3y ago

Feynman on the turn-adapting bit https://youtube.com/watch?v=y7h4OtFDnYE https://youtube.com/watch?v=y7h4OtFDnYE