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High speed trains?

  1. Dec 14, 2009 #1
    well, if i recall correctly, i read that india can't have high speed trains as the rails can't withstand the pressure and are too twisting and turning.
    1) are these the only reasons india can't have high speed trains?
    2) i read somewhere UK had the same kind of rails but they solved the problem by some new 'revolutionary' technology. can anyone enlighten me on this?
    thank you
     
  2. jcsd
  3. Dec 14, 2009 #2
    Rails are a big bottleneck for high-speed trains. In Poland alot of the trains are slow, too, mainly because the rails are still old school. Wooden spacers, not welded, etc.

    I took a train from Poland and through Check republic once. Once it crossed the border, it accelerated to 2-3x the speed. Same exact train.

    I'm pretty sure UK has proper rails. At least compared to India.
     
  4. Dec 14, 2009 #3

    Ranger Mike

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    i suspect it is geography that prevents ultra high speed rail in India country wide
    plate tectonics being one
    lot of earth quakes
    steep terrain
    Mt Everest is in the region
    sunami caused mucho death a few christmas's ago
    i would not want to be riding along a 200 mph plus and find the rail was out
     
  5. Dec 14, 2009 #4
    Look at Japan. They have all sorts of crazy terrains/ tsunamis/ islands/ earthquakes/ godzilla, and yet they have some of the best high-speed trains. In the end it comes down to money. High speed trains need quality rails, and the poorer countries just can't afford them.

    Poland got into the European Union, and the first things they started doing was upgrading their roads/ rails.
     
  6. Dec 14, 2009 #5
    its not just the rails, its road base, too. the train both pounds the rail, and bends up a "bow wave" ahead of the locomotive thats what slowly pulls up spikes. as speed increases it just compounds the problem. a lot of india's rail is of the older, lighter weight style, and (I am pretty sure) wooden ties and not been maintained/upgraded like europe's system Japan has moved to concrete ties, and along with the french, pioneered and perfected the whole welded rail (ribbon rail) style. it is very expensive to rip up rail, rebuild road bed, then new ties and rail, all while keeping the transportation running.

    dr
     
  7. Dec 14, 2009 #6

    brewnog

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    Our rail network is crap. Typically £80-120 for a return trip from here to London (~160 miles), no guarantee of a seat, and it'll usually be late.

    Don't choose the UK as your benchmark, try somewhere in Eastern Europe.
     
  8. Dec 15, 2009 #7
    india rails do have concrete ties.(they're the base planks, right?). but we don't have any high speed trains. highest is shatbdi express(circa 140 kmph).
    dr. dodge, this bow wave you talk about, can we use a suspension system at base to lessen the effect? if so, is it better than replacing the whole rail?
    mr. brewnog, i read somet5hing about rails in UK being able to bend along curves for faster transit. this true?
    thank you
     
  9. Dec 15, 2009 #8
    I am pretty sure the "bow wave" is a function of the mass of the locomotive, and the amount of "settle" in the road bed that makes the ties/rail sink at the wheels and bend up ahead of the locomotive. On some excursion railroads I have been involved with you can really see the effect with the naked eye due to old balasting (rock fill under and between ties) at high speeds this bow wave stacks up over distance doing almost an extrusuion of the railsto push it along.

    dr

    dr
     
  10. Dec 15, 2009 #9
    Come on boy, its not always the engineering why we dont have high speed trains, look at the management, the politics, the system behind it. Yes they can do if they want to, but i dont see any visionary in the system as of now.

    Alot of rail track in india was laid down decades back, it hasnt been upgraded that regularly.

    @ranger, India is a huge country, we dont see earthquakes every now & then, thats rare actually. Tsunami was no where the railway lines & Mt Everest is wayyy up north, no rail lines there also. Lolzz.... :)
     
  11. Dec 16, 2009 #10

    Ranger Mike

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    thanks
    now we know the skinny for that great country
    merry christmas
    rm
     
  12. Dec 16, 2009 #11
    i think it's becasue we have too much population. i mean, we have 10-15 wagons for every train minimum. would take a lot of power to pull so much load at high speeds.
     
  13. Dec 16, 2009 #12
    India's infrastructure is a mess. Bullet trains require a lot of electrical power, and India's power grid is notoriously unreliable. They also require continuously welded rails and sophisticated traffic control systems. It would take many years to recover the initial investment since India is such a poor country.
     
  14. Dec 17, 2009 #13
    i was womdering- could we use lay high voltage elctricity carrying wires on the rails and use the magnetic field produced to lift superconductors, as in maglev trains? how high a voltage should the wires be carrying to lift trains?
     
  15. Dec 17, 2009 #14
    They "could". They "could" also give everybody a personal helicopter and completely make the issue irrelevant. The problem is that even the richest countries in the world have a hard time coming up with the money for the system that you propose. And even if they could come up with the money, they would never get it back. It would be purely for a publicity stunt.

    When you talk about India, whose citizens make probably 50x less than most the countries I'm talking about, you end up running into some problems...
     
  16. Dec 18, 2009 #15
    but the system i propose should reduce costs. they don't have to lay new rails, only cables along the existing ones. and they also trasport electricity from, like, a power station to a grid or something.
     
  17. Dec 18, 2009 #16
    reducing costs does not get something built. only cash outlay does. when that cash is borrowed, then your costs reductions need to be significantly greater than the interest over time. I don't think the residual magnetic field would have enough force to lift the trains. but most importantly, a track bed and guide rails still need to be laid to carry the weight and cornering forces of a VERY heavy train at 150-300 mph. and if the train crashes, the grid goes down.

    dr
     
  18. Dec 20, 2009 #17
    like i said, the already laid rails could serve as guide rails. but more importantly, how much how high a potential do those wires need to be at to lift trains.
     
  19. Dec 20, 2009 #18

    Astronuc

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    Magnetic levitation simply requires a superconductor, usually on the object being suspended, or opposing magnets are required.

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


    High speed rail of the conventional steel wheel-on-rail requires high quality equipment and high quality track and right of way. With high speed comes higher centripetal forces, so the devitation of the track from straight or smooth curve must be very small. Dedicated rights of way must be constructed.
     
    Last edited by a moderator: May 4, 2017
  20. Dec 28, 2009 #19
    well, if we do lay lines and use the magnetic field to lift trains, would it increase the transmission loss?
     
  21. Dec 28, 2009 #20
    IMHO, you'd be better to lay the superconductor as the transmission lines, then float the perm. mag above it
    that way, no transmission loss, data transfer is possible, and the grid is protected vs winds

    dr
     
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