[Xorlev]

Reading through the criticisms the consensus is "sure, this can work if you allocate 10-100x more money than estimated." I'm not sure if it's truly innovative if it costs more, places considerable stress (up to 0.5g!) on the rider/cargo (what the author calls a "barf ride"). The analysis picks apart the touted benefits of additional speed when ultimately the capacity is lower and it takes longer to depart. In the case of cargo, the author argues that the "last mile" of cargo takes the longest, and as such there's little benefit to sending it at 1200kph if it then needs to be offloaded and trucked around anyways.

To summarize:

- construction costs are underestimated or completely wrong

- capacity is lower than standard HSR

- Hyperloop claims power usage is higher for HSR than it actually is

- forces aren't adequately accounted for even with canting

- assuming perfect canting the pylons must take the additional force

- the majority of travel time is to/from the station + security screening.

To me, it seems like it's optimizing for the wrong section of the trip.

[notahacker]

I think the biggest point the article makes is the great deal of care that needs to be taken in packing loads to meet weight requirements and avoid movement of goods in transit.

What makes sense for international air mail doesn't make sense for a four hour journey by truck, especially if that truck can take a container straight from the ship to the city depot without carefully repacking everything, or go door to door with smaller loads.

[woodpanel]

Yes. With what exactly does freight-hyperloop try to compete? Trucks are more flexible while freight rail is struggling on most routes and speed seems of least concern there.

[bwilliams18]

Maybe I'm totally unaware, but don't trucking, air freight and sea freight have the same problems w/ regards to weight requirements and movement of goods in transit? Is this not a solved problem? Build Hyperloop Freight to fit a ULD and we're all set no?

[notahacker]

As the article notes, goods would move a lot more when they're subjected to the G-forces of a hyperloop than the occasional rolling of a ship or even much milder G-forces of an aircraft taking off, which they have to be packed pretty carefully for as is. And whilst all transport methods have a weight limit and some degree of load-balancing requirement, it's much more of a restriction for the load of a capsule fired at supersonic speed through a curving tube that has to resist forces imposed upon it than a bigger lorry chugging along at a sedate 60mph.

[jdmichal]

Container ships will have a dozen plus containers loaded across. Even if all the cargo shifted to one side of each container, the general balance of the vessel would remain roughly the same.

[taneq]

A train that accelerates at 0.5g to 1200kph would be awesome and I would ride it at every available opportunity.

[sib]

The issue is not acceleration front/back, which can be dealt with in design and is fairly stable and consistent, but acceleration as much as 0.5G side/side, which is also more intermittent and against which it's difficult to build seats that would protect customers.

[Retric]

Really it's just a question of track design as these are 100% predictable G forces. If you really need to turn you can just roll the cabin and keep these g's directly under you and or slow down apraoching it. Elevators can also quickly have a fairly wide range (0.8 to 1.2) g's and people don't really get sick in them.

Highways for example have fairly wide banks which people rarely notice. https://sterlingpearce.files.wordpress.com/2015/02/img_0054....

[toomanybeersies]

Aeroplanes are probably a more accurate approximation of what you'd feel. You get hardly any G force from banked highways, your speed is just too low. Now I don't really get plane sick, I will quite happily sit through a few barrel rolls (which is far more extreme than the hyperloop (although that would be fun)), but there's plenty of people who would get sick from a few 1.5 G banked turns.

Elevators are different because you don't spend more than about 1 minute in an elevator.

[Retric]

High end cars can pull up to 1g lateral forces and many cars can pull up to 1g breaking on a good road surface. Relatively low top speed just means you don't accelerate very long. I have hit weightlessness over a hill at high speeds followed by 1.x g on the other side, so 0.5 g does not seem bad.

Remember 1g * 1 second is only ~22mph.

[toomanybeersies]

For sure, my car is a pile of junk and can hit 1g braking.

The problem is when it's sustained. That's why people get sick on roller coasters and when doing aerobatics (extreme examples, I know).

[Lazare]

That doesn't really solve it; there's limits on how much you can rotate the cabin, and how quickly you can rotate it. Lots of math here: https://pedestrianobservations.wordpress.com/2013/08/13/loop...

[mypalmike]

What about one where you feel that, acting in various directions, at every curve, every speed transition, and every elevation change. Because that's the "barf ride" being discussed, not merely getting thrown to the back of your seat during initial acceleration.

[taneq]

That sounds even more fun. :D

Although as the poster mentioned below, a passenger service would gradually rotate the passenger compartment to keep the G-forces vertical, a la a banking aircraft, so all you'd likely notice would be feeling heavier for a few seconds.

[Lazare]

The "barf ride" comments were the result of calculations which included rotating the passenger compartment.

See https://pedestrianobservations.wordpress.com/2013/08/13/loop... linked from the original article.

[taneq]

Interesting link, thanks! I should have clicked more on the original article. :)

This seems to be the comment in question:

> This is worse than sideways acceleration: track standards for vertical acceleration are tighter than for horizontal acceleration, about 0.5-0.67 m/s^2, one tenth to one seventh what Musk wants to subject his passengers to. It’s not transportation; it’s a barf ride.

I find the statement that vertical acceleration is 'worse than sideways acceleration' to be highly suspect (otherwise why would you bother to bank into turns?) - I would guess that the track standards are for +/- 0.5ms^-2 and mostly target short-period up-and-down bouncing motions rather than smoothly applied upwards acceleration.

[mypalmike]

The analysis suggests that the speeds involved would require a few minutes of said g-forces, not seconds.

[ansible]

Yeah, seriously. I'd fly out to California just to take a trip on it.