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Comment by djpilot | Hacker News Reader

I really like the bendy train in the artistic rendering. What materials would allow for railroad car chassis and bodies which could bend and torque with the curve of the track like rubber? I think you would need lots of wheels or a relatively pointless flex-inducing system on each car to even get it to bend in this fashion.

Perhaps it just made for a pretty picture, and a completely impractical reality :)

https://i2.wp.com/www.mercurynews.com/wp-content/uploads/201...

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Not quite a bendy train but the Toronto Rocket subway is quite a trip during sharp turns, as it has fully-open gangways, giving the appearance that the train is bending through curves.

https://en.m.wikipedia.org/wiki/Gangway_connection#/media/Fi...

The artist just doesn't understand physics. Even if it was possible, you'd be losing huge amounts of energy to constant deformation.

I don't think this is correct as a general statement. Imagine if the walls were made of canvas fabric with appropriate amounts of slack, just as an example of a material that can easily bend.

You would need a cleverly designed frame, but I'm sure there is something that would work. Perhaps many smaller segments joined together.

Canvas can bend more easily than rubber or steel, but deforming it still requires some energy. And while canvas would work for the walls, it wouldn’t work for the bogey, and anything rigid enough to work as a bogey would take lots of energy to bend.

To some extent you can say a regular multi-bogey train is undergoing deformation by changing the angular configuration between cars via the linkages. This could technically be extended to have the linkages have every few inches along the bogey instead of between 20-foot segments. We just need a way to transfer energy reliably between deformations and change in acceleration.

Alternatively, maybe it has nothing to do with physics, the picture is computer rendered, and the artist found the first of these two alternatives a whole lot easier:

1. model a train that is straight, and then use some tool to bend the entire model to fit a curve.

2. define a curve, then align models of train engine and cars so that they follow the curve.

If the train is elastic, you'd recover that energy.

Going into a curve, kinetic energy from the speed of the train is turned into spring energy by bending the train. Leaving the curve, the spring energy becomes kinetic energy. The flexed train speeds up due to the spring force as the train unflexes.

I also appreciate the re-used formation of Tesla/van/Tesla next to Smart car/Smart car/Smart car.

And all of the vehicles are not just driverless -- they're passenger-less!

I still like it. Probably means everyone is finally working from home.

oh man, I've come here to complain about unbelievably small radiuses. But they bent the damn train car!

Steel tracks are transported on trains and they flex: https://www.instagram.com/p/Bt6SgeQHA4b/?igshid=1f2ujwjayn8w...

This is OT, but it was absolutely impossible to tap the tiny X on the "use our app" banner. It just opened the clipboard overlay no matter what I tried (Firefox Android) -- tap X, "Select All" button appears.

The first thing that caught my eye was the gap in the middle of the bridge. A rather rare sight in reality, so the presentation of such a rendering comes across as a form of lying.

I completely missed the curved train cars! Thanks for pointing it out.

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