# Would This High Speed Train Work? **URL:** \ **Category:** Great Debates\ **Created:** [July 31, 2008, 9:10am UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337 "2008-07-31T09:10:38Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [July 31, 2008, 9:10am UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/1 "2008-07-31T09:10:38Z")
Years ago, I read about a guy who designed a unique (low teck) high speed train. The idea was based around having cylindrical capsules running in an evacuated tunnels-the trains could attain speeds of 600 MPG, because the tunnel was a vacuum. The trains would be pulled along by electromagenetic induction (NOT MAGLEV)-just coils in the walls. Would this work? ---
**Author:** ![Darryl\_Lict](https://avatars.discourse-cdn.com/v4/letter/d/7cd45c/32.png) [@Darryl\_Lict](https://boards.straightdope.com/u/Darryl_Lict)\ **Post date:** [July 31, 2008, 9:40am UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/2 "2008-07-31T09:40:21Z")
It’s not maglev, but there have been several attempts to build [pneumatic tube trains](http://en.wikipedia.org/wiki/Beach_Pneumatic_Transit). Someone tried to build one in [Manhattan](http://en.wikipedia.org/wiki/Beach_Pneumatic_Transit) in 1870. I somehow seem to recall that it was in the news recently when new construction exposed a portion of it. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [July 31, 2008, 11:13am UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/3 "2008-07-31T11:13:27Z")
[QUOTE=ralph124c] Years ago, I read about a guy who designed a unique (low teck) high speed train. The idea was based around having cylindrical capsules running in an evacuated tunnels-the trains could attain speeds of 600 MPG, because the tunnel was a vacuum. The trains would be pulled along by electromagenetic induction (NOT MAGLEV)-just coils in the walls. Would this work? [/QUOTE] It would work, but the cost per mile of constructing and maintaining it would be stupendous. Here in the US we don’t even have Japanese-style high speed bullet trains, and AFAIK there are no plans to build any. ---
**Author:** ![Grumman](https://avatars.discourse-cdn.com/v4/letter/g/43a26b/32.png) [@Grumman](https://boards.straightdope.com/u/Grumman)\ **Post date:** [July 31, 2008, 11:26am UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/4 "2008-07-31T11:26:41Z")
What advantage does this have over a true maglev train? If it is already using electromagnetic induction to move the train, wouldn’t contact with the walls of the tunnel just slow it down? ---
**Author:** ![Paul\_in\_Qatar](https://avatars.discourse-cdn.com/v4/letter/p/ccd318/32.png) [@Paul\_in\_Qatar](https://boards.straightdope.com/u/Paul_in_Qatar)\ **Post date:** [July 31, 2008, 12:53pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/5 "2008-07-31T12:53:03Z")
Sure it would work. Lots of things work on the level of engineering. Very often it is a chore making the economics pay off. (The transatlantic tunnel and terraforming Mars are my favorite examples.) We could do lots of things if we wanted to pay for them. (How would passengers handle the acceleration and deceleration of such a train?) ---
**Author:** ![Ike\_Witt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ike_witt/32/283_2.png) [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)\ **Post date:** [July 31, 2008, 1:03pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/6 "2008-07-31T13:03:43Z")
[QUOTE=Paul in Saudi] (How would passengers handle the acceleration and deceleration of such a train?) [/QUOTE] Or being stuck in a vacuum? ---
**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\ **Post date:** [July 31, 2008, 1:36pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/7 "2008-07-31T13:36:55Z")
[QUOTE=adam yax] Or being stuck in a vacuum? [/QUOTE] Same way airline passengers deal with being stuck at low atmospheric pressure – sealed, pressurized cabin. ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [July 31, 2008, 1:43pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/8 "2008-07-31T13:43:05Z")
[QUOTE=ralph124c] Years ago, I read about a guy who designed a unique (low teck) … [/QUOTE] Low teck? :dubious: Not by a long shot. ---
**Author:** ![iamthewalrus\_3](https://avatars.discourse-cdn.com/v4/letter/i/258eb7/32.png) [@iamthewalrus\_3](https://boards.straightdope.com/u/iamthewalrus_3)\ **Post date:** [July 31, 2008, 7:17pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/9 "2008-07-31T19:17:51Z")
I’m much more impressed with the idea of the [nonstop train](http://www.transporttrends.com/mvnforum/mvnforum/viewthread?thread=1788) with detachable pods. Unless you’re building an express over a long distance, a significant cost in both fuel and time is accelerating and decelerating the train. Building it so that it’s modular and only certain parts of the train start and stop would go a long way towards making things more efficient. In addition, it doesn’t require any fancy technological improvements, evacuated tunnels or strong electromagnets, just some basic engineering. And it can be seamlessly integrated into the existing network because the train can continue to stop at any station that’s not fitted for a detachable pod. ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [July 31, 2008, 7:40pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/10 "2008-07-31T19:40:45Z")
[QUOTE=Paul in Saudi] (How would passengers handle the acceleration and deceleration of such a train?) [/QUOTE] Humans can withstand acceleration of up to 45 _g_. Doing so comfortably is a different question. :smack: 😉 ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [July 31, 2008, 8:11pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/11 "2008-07-31T20:11:59Z")
[QUOTE=Grumman] What advantage does this have over a true maglev train? If it is already using electromagnetic induction to move the train, wouldn’t contact with the walls of the tunnel just slow it down? [/QUOTE] Less air resistance - which could be crucial if you want, say, to link [two continents](http://en.wikipedia.org/wiki/Tunnel_Through_the_Deeps) together, and don’t want to have to push a thousand-mile-long plug of air in front of you. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [August 4, 2008, 2:24pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/12 "2008-08-04T14:24:27Z")
[QUOTE=Malacandra] Less air resistance - which could be crucial if you want, say, to link [two continents](http://en.wikipedia.org/wiki/Tunnel_Through_the_Deeps) together, and don’t want to have to push a thousand-mile-long plug of air in front of you. [/QUOTE] Wouldn’t it be easier to build powerful vacuum pumps along the line to evacuate the air as a train approaches (lowering the air pressure in front of it) and then refilling the tunnel after the train passes, giving the train an additional push? Of course, it would be easier still and immensely cheaper to fill the air with 21st-century Concordes, but no matter. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [August 4, 2008, 4:10pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/13 "2008-08-04T16:10:44Z")
Because the loading is compression, rather than tension as for a pressure vessel, the walls of a vacuum chamber need to be very stout. This scales non-linearly, so for a train sized tunnel, I’d wag you’d need steel walls at least 4" thick. That is one helluva lot of steel. Oh yeah, if you want to use inductive drive, then the walls can’t be steel, or even a non magnetic conductor (eddy current losses)…so fiberglass maybe? ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [August 4, 2008, 5:41pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/14 "2008-08-04T17:41:46Z")
[QUOTE=Bryan Ekers] Wouldn’t it be easier to build powerful vacuum pumps along the line to evacuate the air as a train approaches (lowering the air pressure in front of it) and then refilling the tunnel after the train passes, giving the train an additional push? [/QUOTE] Rather than lots of pumps and ducts along the length of the tunnel, just have one pump in the train; sucks air in at the front, and blows it out the back. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [August 4, 2008, 5:52pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/15 "2008-08-04T17:52:35Z")
[QUOTE=Robot Arm] Rather than lots of pumps and ducts along the length of the tunnel, just have one pump in the train; sucks air in at the front, and blows it out the back. [/QUOTE] I think that idea both sucks…and blows. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [August 4, 2008, 6:16pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/16 "2008-08-04T18:16:32Z")
[QUOTE=Robot Arm] Rather than lots of pumps and ducts along the length of the tunnel, just have one pump in the train; sucks air in at the front, and blows it out the back. [/QUOTE] And maybe if the pump was powerful enough, you might not even need the track. That train could, I dunno, “fly” or something. ---
**Author:** ![Weirddave](https://avatars.discourse-cdn.com/v4/letter/w/919ad9/32.png) [@Weirddave](https://boards.straightdope.com/u/Weirddave)\ **Post date:** [August 4, 2008, 6:33pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/17 "2008-08-04T18:33:49Z")
[QUOTE=Darryl Lict] It’s not maglev, but there have been several attempts to build [pneumatic tube trains](http://en.wikipedia.org/wiki/Beach_Pneumatic_Transit). Someone tried to build one in [Manhattan](http://en.wikipedia.org/wiki/Beach_Pneumatic_Transit) in 1870. I somehow seem to recall that it was in the news recently when new construction exposed a portion of it. [/QUOTE] Was it filled with a river of slime? 😉 Actually, from your link: > [@](#): > > In 1912, workers excavating for the present-day Broadway Subway dug into the old Beach tunnel, where they found the remains of the car and the tunnelling shield used during initial construction. The shield was removed and donated to Cornell University, which has since lost track of its whereabouts. The tunnel was demolished to build the BMT City Hall station. Beach’s original station, built in part of the basement of Devlin’s clothing store at the corner of Warren Street and Broadway, had long since been reclaimed for other uses. Just how old are you that 1912 is “recently”? :dubious: Maybe you should see if the screen name “Methuselah” is available. 😃 ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [August 4, 2008, 7:21pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/18 "2008-08-04T19:21:00Z")
And if there was every an accident with one of these trains, one can be assured it would always be a recovery operation. If the massive deceleration didn’t kill the crew and passengers, the vacuum certainly would. ---
**Author:** ![Mark\_Ryle](https://avatars.discourse-cdn.com/v4/letter/m/8dc957/32.png) [@Mark\_Ryle](https://boards.straightdope.com/u/Mark_Ryle)\ **Post date:** [August 4, 2008, 8:25pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/19 "2008-08-04T20:25:49Z")
[QUOTE=iamthewalrus(:3=] I’m much more impressed with the idea of the [nonstop train](http://www.transporttrends.com/mvnforum/mvnforum/viewthread?thread=1788) with detachable pods. [/QUOTE] There would be no waiting for people to board or disembark. Here’s a video of a [nonstop train network](http://www.youtube.com/watch?v=HeGZDXLB8GM). ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [August 4, 2008, 8:32pm UTC](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337/20 "2008-08-04T20:32:47Z")
I saw something similar on some show about building a hypothetical trans-Atlantic rail tunnel. But I thought the trains were maglevs and would reach speeds of several thousand miles an hour in a vacuum. [Next page](https://boards.straightdope.com/t/would-this-high-speed-train-work/458337.md?page=2)