[dragonstar57]

i know someone who says that someday a system of Pneumatic tubes
( http://en.wikipedia..../Pneumatic_tube ) will replace cars.
this seems absolutely ridiculous to me. and i was wondering if someone could confirm how absolutely ridiculous it is and explain the many reasons why it is so ridiculous.

This post has been edited by cipher510: 5 September 2010 - 05:26 PM

[insane_alien]

its not actually THAT ridiculous.

i don't think it'd replace cars, but it could defnitely work for a replacement to subway trains. just evacuate(or partially evacuate) the tunnels and propell the cars by using the atmosphere.

[Klaynos]

Have a look in wp for brunell's atmospheric railway...

[Marat]

There also used to be a pneumatic tube system for mail delivery all around Paris which worked quite well until the increased availability of the telephone made it obsolete. The tube system is still there under Paris today, but no longer in operation.

[lemur]

I think I heard that there were plans to build cycling tunnels close to Amsterdam with controlled wind flow for speed-assist. I wonder what ever happened to that.

[JohnB]

Alfred Beach had one running under New York back in 1870.

[the tree]

cipher510, on 5 September 2010 - 05:25 PM, said:

i know someone who says that someday a system of Pneumatic tubes
( http://en.wikipedia..../Pneumatic_tube ) will replace cars.
this seems absolutely ridiculous to me. and i was wondering if someone could confirm how absolutely ridiculous it is and explain the many reasons why it is so ridiculous.

Can you think of any reasons off of your own back? It's not exactly scientific, to pick a conclusion, and then find a way to get there.

insane_alien, on 5 September 2010 - 05:29 PM, said:

its not actually THAT ridiculous.

i don't think it'd replace cars, but it could defnitely work for a replacement to subway trains. just evacuate(or partially evacuate) the tunnels and propell the cars by using the atmosphere.

Using the underground is already more sensible than using a car in a densely populated city. It's in rural areas where mass transportation doesn't make sense, that personal cars are going to stick around.

[dragonstar57]

there would be almost no way to turn. and it would a horizontal one even work?

[Frank White]

Well the population of the earth in the year 5620 could be 300 trillion for all we know maybe more
At some point every square inch of the land and ocean will be altered by humans. After that we have to build up and build down into the ground. Imagine the earth with a shell over it. This shell is actually a one world building. This world building could be a few miles high and many miles deep into the earths crust. It would need to be this way to support hundreds of trillions of people. Would look something like the death star from star wars

So in this case there would be no room for roads. You need to access areas deep within the shell so tubes are the only way. Even if its a road in a hollowed tunnel.... well thats a tube. Also by this year there will surely be no such thing as cars. Thats like humans today riding horses as our main transportation lol. By then we will probably not need to move. Each human would not even be genetically human by then but lets say they were. they would probably be linked to the internet and never leave there brain uploading station. But lets say they still do want to travel around the physical world. If they did travel they would have no choice but to use tube like transportation. It is probably inevitable if we still move from one place to another in the future. It would probably be some advanced maglev transport system of tubes thats all automated.

This post has been edited by Frank White: 10 September 2010 - 07:28 PM

[insane_alien]

cipher510, on 10 September 2010 - 06:59 PM, said:

there would be almost no way to turn. and it would a horizontal one even work?

eh? how would there be almost no way to turn? thats like saying trains have almost no way to turn yet those seem to work just fine.

and why wouldn't a horizontal one work?

[dragonstar57]

but why not just make subways the "transportation of the future"?

[JohnB]

Frank White, it sounds like you are describing Trantor, or one of the "Caves of Steel".

[the tree]

Well, there probably wont be a 'transport of the future'. There's never going to be a need for a single form of transport. But there's no reason to suspect that pneumatic tubes will never become popular in some context - perhaps one where having an engine on every individual train becomes impractical (an underground equivalent to maglev, perhaps?).

[dragonstar57]

how would it stop? and if it was a huge system how would you pressurize the whole thing?
the whole idea of it being a form of transportation sounds impracticable and for transportation of data it would need to be beater than a network

[wright496]

Frank White, on 10 September 2010 - 07:24 PM, said:

Well the population of the earth in the year 5620 could be 300 trillion for all we know maybe more
At some point every square inch of the land and ocean will be altered by humans. After that we have to build up and build down into the ground. Imagine the earth with a shell over it. This shell is actually a one world building. This world building could be a few miles high and many miles deep into the earths crust. It would need to be this way to support hundreds of trillions of people. Would look something like the death star from star wars

So in this case there would be no room for roads. You need to access areas deep within the shell so tubes are the only way. Even if its a road in a hollowed tunnel.... well thats a tube. Also by this year there will surely be no such thing as cars. Thats like humans today riding horses as our main transportation lol. By then we will probably not need to move. Each human would not even be genetically human by then but lets say they were. they would probably be linked to the internet and never leave there brain uploading station. But lets say they still do want to travel around the physical world. If they did travel they would have no choice but to use tube like transportation. It is probably inevitable if we still move from one place to another in the future. It would probably be some advanced maglev transport system of tubes thats all automated.

I would hope that by that time we will have started colonizing space.

[Klaynos]

Seriously look up the atmospheric railway. It successfully moved goods and carriages around for a while. Just the rats liked the taste.

[CaptainPanic]

I was thinking: is it acceptable if the pressure behind the train (the air that pushes the train) is lost when the train enters a station? (I'm not talking about safety: the possible hurricane wind forces in the station if a complete tunnel at higher pressure empties itself into the atmosphere, through the station!).

The pressure behind the train must be higher than the pressure in front of it... Take a 100 ton train. Assume an acceleration if 1 m/s2. Assume a snug fit in a pipe of a diameter of 5 meter.
F = m*a = 100,000 * 1 = 100,000 N
F = P*A => P = F/A = 100,000 / (2.5^2*pi) = 5092 Pa, or 51 mbar.

Now, we assume a tunnel of a length of 100 km
W = P1 * V1 * ln(P2/P1)
W = P1 * length*(0.5*diameter^2*pi) * ln(P2/P1)
W = 100,000 * 100,000 * (pi*2.5^2) * ln (105092/100,000) = 9.8 GJ.
If that tube segment receives just 1 train in 1 hour (3600 seconds) then the power requirement is 2.7 MW.
That's about the same as a modern electric locomotive for regular trains...


Other issues:
- The air itself also moves, causing turbulence, and increasing energy demand
- The energy consumption goes up with every train (more trains in a tunnel means a higher pressure is required)
- The energy consumption goes up linearly with the length of the tunnel sections
- Even if all the problems are solved, there will still be a massive number of compressors... because tunnels will continuously be compressed and evacuated... and it all sounds just a bit complicated for

Personally, I see more future in complete vacuum tubes. Insert the train through an airlock, and make it run like a maglev. It's complex to build, but at least the energy requirements are only for the kinetic energy of the train, and not for massive compressors... and the energy consumption does not go up linear with the length of the tracks!

This post has been edited by CaptainPanic: 12 October 2010 - 12:15 PM

[Klaynos]

Don't push the whole train, just push a part of it, or something connected to it.

http://www.damninter...ic-people-mover

http://www.exetermem...ric_railway.php