
Hyperloop: Not so fast - cju
http://blogs.mathworks.com/seth/2013/11/22/hyperloop-not-so-fast/
======
jcchin41
NASA engineers have also released an optimization framework for the Hyperloop
concept as well. It's completely open-source and written in Python. Docs here:
[http://openmdao-plugins.github.io/Hyperloop/](http://openmdao-
plugins.github.io/Hyperloop/)

Their baseline optimization focuses on 5 subsystems: Compressor Cycle
Analysis, Pod Geometry, Tube Flow Limitations, Tube Wall Temperature, and
Mission Analysis

Initial results indicate that the concept is still very viable. However, due
to very tight coupling between the tube and vehicle size, the tube size will
need to be around twice as large as originally proposed by the Tesla/SpaceX
team to reach the proposed speeds.

Feel free to download the entire analysis and play with it yourself, without
purchasing several expensive toolboxes from MATLAB!

~~~
justingray
As one of the authors of this work, I would like to add that our goal was to
provide an open source foundation for modeling the hyperloop system. Our
initial work focused on the pod itself, but we want to expand it to include
trajectory analysis as well as cost modeling.

~~~
omegant
Hi Justin, do you have an email to reach you or some body else at the team?

~~~
justingray
you can reach me at justin.s.gray@nasa.gov

------
bane
I remember hearing an interview with a civil engineer about why highways have
all these "unnecessary" curves in them. Why can't engineers build highways
that are more direct and straight?

After going on a bit about requirements for different kinds of terrain, the
kind of strata the road needs to go on etc. and how those were difficult and
expensive to surmount (so curves were often chosen to deal with it instead of
a more expensive solution). He lamented that the _most_ difficult and
expensive aspect of new road construction was right of way through existing
developments and other properties. Most of the curves we experience on
highways are apparently the result of somebody, or a block of people, simply
not wanting to give up their land.

~~~
BrandonMarc
Fatigue, boredom, and monotony are a factor, too. I watched an episode of
Modern Marvels on the History Channel [0] which gave interesting details about
the highway system. They mentioned something they called "highway hypnosis"
[1], a trance-like state which they wanted to avoid. There's been some
discussion of whether this phenomenon is to blame for the train derailment in
New York about a month ago [2].

 _Most of the curves we experience on highways are apparently the result of
somebody, or a block of people, simply not wanting to give up their land._

Nor should they have to, if they don't want to (or disagree on the price).

\----------------------------------------

[0] [http://www.history.com/shows/modern-
marvels/episodes/season-...](http://www.history.com/shows/modern-
marvels/episodes/season-3) ... see "Paving America" for the episode

[1]
[http://en.wikipedia.org/wiki/Highway_hypnosis](http://en.wikipedia.org/wiki/Highway_hypnosis)

[2] [http://www.foxnews.com/us/2013/12/05/deadly-new-york-
train-d...](http://www.foxnews.com/us/2013/12/05/deadly-new-york-train-
derailment-could-be-case-highway-hypnosis/)

~~~
ivanca
>Nor should they have to, if they don't want to (or disagree on the price).

This is a real issue in many places now; when building a transportation system
the government should be able to pay you whatever the house is valued and give
you no saying on that, why? because the mobility of millions is more important
than your emotional attachment to the house.

~~~
gizmo686
I don't know how it actually works, but I would hope if the government uses
its right to force you to sell your land, which the US (and likely others)
does have under eminent domain, that they would pay above market price. Market
price would cover the cost of you purchasing an equivelent home, it would not
compensate you for moving expenses, time, possible lost wages, ETC.

~~~
deelowe
The government's "market prices" and the real value of a property are two
totally different things. There is downward pressure to keep the government
assessments low due to property taxes. Where I live, for example, the prices
are generally off by a good -10% to -20%. Then you have to add interest,
closing costs, escrow, and establishment of utilities on top of that.

You also have to factor mobility into the equation. If I own property that I'm
using for a special purpose (let's use an extreme example of a hazardous
chemical disposal company), and I'm told to relocate for the "market price" of
my property, then I'm stuck paying tons of money and dealing with regulatory
hell in whatever I choose as my new jurisdiction to do this. This would quite
literally put me out of business due to the insanely high cost of relocating
everything.

Also, you have the legal roadblocks that often come up (this is the more
common reason property can't be acquired). For example, the property might be
owned by a trust, which was granted it's powers through a will. Since it's a
trust, the beneficiaries are unknown. The person who maintains the trust isn't
returning your calls. Who do you write the check to? You can't just take it
from the trust, it doesn't work that way (for good reason, without getting
into specifics). There are ways to go about it, but the legal proceedings can
take years. We're actually dealing with this exact problem now trying to
expand an intersection in my local town.

Unfortunately, it's not as simple as just buying the land/structure and moving
the occupants. More often than not, there's a reason why this is difficult.

~~~
mapt
It seems like the price of the various measures that avoid invoking eminent
domain ends up being so extraordinarily high (hundred-million-dollar bridge
trusses and the like), I do not quite understand why offering market plus 100%
or something isn't a solution. Not an extortionate rate, but one sufficient to
make it a financially favored course of action for all involved landowners.
Eminent domain is for the irrational holdouts, not for "offering pennies on
the dollar" as opponents say, or for getting just-slightly-submarket-prices.

~~~
gizmo686
The problem is that the only people who can say how much money is necessary is
the landowners themselves. However, they have an incentive to lie if doing so
would allow them to get a higher price. Additionally, different landowners
would value their own land at a significantly different rate relative to the
market. For example, if you live in a custom built house, with a treehouse
that your kids built themselves, that is within walking distance to the school
and your place of work, you would need significantly more compensation them
most people to move out of your house. I don't see any solution other than
letting cases where an agreement cannot be reached go to court.

~~~
mapt
There are three people are well-placed to say how much money is 'market
value':

1) The owners themselves, by self-declaring asset values for taxation purposes
(on pain of having them vulnerable to eminent domain seizure if they under-
declare)

2) Independent assessors who do value assessment for property tax purposes
already

3) The sellers that granted the owners possession for a certain value

------
kinofcain
Passengers are much more sensitive to vertical acceleration than horizontal.
Repeated 1g swings from -0.5 to 0.5 g would make this thing a vomit comet.
Would be interesting to see this analysis done with normal limits for high
speed rail design, instead of Elon's chosen 0.5g limit.

Edit: HS2 in Britain, for instance, is being designed with a maximum of around
0.01g vertical acceleration. If Elon's has figured out how to get passengers
to handle 50x that much, he could save them a lot of money.

~~~
morsch
Vertical acceleration refers to acceleration in the direction of the tracks,
right?

Some other figures I could find:

Shinkansen: 2.6 km/h/s = 0.07g

ICE (German HSR): 0.5 m/s2 = 0.05g

S-Bahn (metro transport): 1 m/s2 = 0.1g

Makes sense that metro transport has higher acceleration, as high speed rail
spends a lot of time "cruising" at certain speeds, while metro transport is
basically always either accelerating or decelerating. I'd guess subways also
feature relatively high g-forces.

Also interesting:
[http://en.wikipedia.org/wiki/Orders_of_magnitude_%28accelera...](http://en.wikipedia.org/wiki/Orders_of_magnitude_%28acceleration%29)

~~~
lmm
Vertical as in up-down. You're much more comfortable accelerating forwards-
backwards or left-right.

~~~
cma
Then change the orientation of the seats? Without a reference frame you can't
tell.

~~~
modoc
Gravity?

~~~
dspeyer
Include that in the calculations. There's a certain absolute sideways g-force
(decreasable by slowing or straightening), and a certain absolute downwards
gravity. These add up to a single total force. So long as the magnitude is at
least 1g, there exists a seat orientation such that the passenger feels 1g
toward the seat and something on the back.

How much you can spin the seat without _those_ movements causing problems is
an open question.

Airplanes are an encouraging precedent. They often make quite sharp turns at
extremely high velocity, but tilt into them such that there's almost no
perceived lateral acceleration.

------
skj
Despite the headline, which I'm going to assume was added by an editor, the
article is positive about the hyperloop prospects.

~~~
jasallen
It's a pun, not actually a 'negative' headline.

~~~
JTon
To me, it's read as both a pun and a negative headline. I'm surprised others
don't see it that way as well

~~~
protomyth
"not so fast" is generally a nice way of telling someone to stop and consider
what they are doing because they are about to do something unwise. I do
believe you are correct to take the headline as negative.

------
melling
Maybe someone can convince China to develop the technology. They already have
6,200 miles of high-speed rail, on their way to 10,000 miles.

[http://en.wikipedia.org/wiki/High-
speed_rail_in_China](http://en.wikipedia.org/wiki/High-speed_rail_in_China)

Their Shanghai Maglev only cost $1.2 billion.

[http://en.wikipedia.org/wiki/Shanghai_Maglev_Train](http://en.wikipedia.org/wiki/Shanghai_Maglev_Train)

China is clearly interested in building a 21st century transportation
infrastructure. Beijing to Shangai is 800 miles. Perfect for 700 mph
hyperloop.

~~~
us0r
Shanghai does not have the prevailing wages CA has.

~~~
illumen
Shanghai is extremely wealthy... even if you don't account for the accounting
tricks played by china with their currency. Have you ever been? It's like
being transported into the future.

Apparently 20-30% cheaper than places in CA for most things, but to buy an
apartment it's more expensive.

Wages are 75% or so cheaper in Shanghai, but purchasing power is 66.36% lower
too... [http://www.numbeo.com/cost-of-
living/compare_cities.jsp?coun...](http://www.numbeo.com/cost-of-
living/compare_cities.jsp?country1=United+States&country2=China&city1=Oakland%2C+CA&city2=Shanghai)

~~~
throwaway_yy2Di
_" Shanghai is extremely wealthy..."_

Seriously? The mean household income is US$4,700/year [0] (nominal
conversion). Your link claims it's $12,000/year for an individual, but if you
investigate further, that's the mean of the high-income expats _who visited
that English-language website about international costs of living_ and filled
out a survey. The very existence of this large expat population skews the
mean; I'd guess "typical", median wages are a lot lower than $4,700.

[0] " _Average annual income for a family in 2012 was 13,000 renminbi, or
about $2,100. When broken down by geography, the survey results showed that
the average amount in Shanghai, a huge coastal city, was just over 29,000
renminbi, or $4,700, while the average in Gansu Province, far from the coast
in northwest China, was 11,400 renminbi, or just under $2,000. Average family
income in urban areas was about $2,600, while it was $1,600 in rural areas._ "

[http://www.nytimes.com/2013/07/20/world/asia/survey-in-
china...](http://www.nytimes.com/2013/07/20/world/asia/survey-in-china-shows-
wide-income-gap.html)

~~~
Vardhan
Being wealthy isn't just about income, it's about what you can do with your
income.

~~~
xorblurb
$13000 "brut" in Shanghai is approx $20000 PPP according to
[http://en.wikipedia.org/wiki/List_of_Chinese_administrative_...](http://en.wikipedia.org/wiki/List_of_Chinese_administrative_divisions_by_GDP_per_capita)

Income of $5000 would be approx $7700 PPP. Not exactly extremely wealthy by
developed countries standard...

------
cju
Another article of the blog is about the modelisation of the Hyperloop
vehicule (+environment):
[http://blogs.mathworks.com/seth/2013/11/07/hyperloop-
model-a...](http://blogs.mathworks.com/seth/2013/11/07/hyperloop-model-
architecture-we-want-your-feedback/) It can be read as an introduction to
Model Based Design. It shows for instance the interest of handling variants to
test either different hardware concepts or different level of
representativity.

------
mrfusion
Personally I'm still worried about the claustrophobia issues. And I'm not even
really claustrophobic.

There's just something about being in a small seat in a concrete tube with no
exit for 100's of miles that really freaks me out.

~~~
jonknee
Are you afraid to fly? An aluminum tube with no exit for thousands of miles
and a much longer time in the seat.

~~~
ceejayoz
Planes have windows and the ability to get up and walk around to some extent.
Likely makes a difference for most claustrophobics.

~~~
blowski
Does the design of Hyperloop make it impossible to walk around?

In terms of no windows, sounds similar to the Channel Tunnel. You're typically
in the tunnel for close to 30 minutes.

~~~
deletes
Yes, in the passenger version you can't even stand up.

You would probably have a huge interactive flat screen in front of you to ease
the tension.

------
dangerlibrary
Article assumes that the hyperloop can/would follow existing highways.
Considering the cost of diverting traffic during construction, it seems
unlikely you could build it for anything close to the advertised $6 billion
while following existing highways.

Also, the structure would need to be tall (or short) enough to bypass highway
bridges and overpasses...

~~~
sargun
The Hyperloop design paper states that it would be along existing highways.

~~~
dangerlibrary
I missed that! Thank you.

~~~
dasil003
Did you change your original comment because this thread makes no sense.

~~~
dangerlibrary
I did not change anything. I was nitpicking about something implied in the
linked article, without realizing it was in Musk's original spec/budget.

------
pbreit
A fun article and exercise but a bit suspect since the only image of a
difficult turn is not one the hyperloop is actually scheduled to take (the
design document linked shows the route continuing straight along HWY 238 at
that point). But the next turn north along 880 looks tricky (it looks like
there might be some room at the school, cemetery and empty lots to smooth it
out a bit).

------
penrod
My only objection to Hyperloop is that it's so damned _ugly_. What ought to be
an inspirational feat of engineering looks, under the proposed pillar design,
like an elevated oil pipeline. I can't imagine anyone wanting to look at it,
let alone having it blight their property.

It's a shame they haven't proposed a graceful cable-stayed structure.

------
NAFV_P
This reminds me of the Red Bull X1 out of GT5. I remember going round a
hairpin at 250km/h, that's bound to snap your neck.

