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High Speed Travelator

Posted by ryuzaki0 on from the umbrella-jousting dept.

Anonymous Award writes "Remember those old Isaac Asimov tales of cities of the future, where everybody walked along on moving sidewalks, sometimes clear across a country? Today's airport travelators have always been disappointingly pale imitations of these, but now in Paris we may be seeing the true birth of this wonderfully dangerous mode of mass transportation. Its already as fast as a bus, but when they can crank them up to motorway speeds... well, lets just say this may have a better chance of having cities designed around it than certain other recent innovations."

14 of 333 comments (clear)

  1. You know... by Anonymous Coward · · Score: 4, Interesting

    When it gets up to a certain speed, the wind resistance against your body will be greater than the friction of the belt against your feet, and you will cease to move forward...

    1. Re:You know... by klaasvakie · · Score: 5, Interesting

      When it gets up to a certain speed, the wind resistance against your body will be greater than the friction of the belt against your feet, and you will cease to move forward...

      IANAP either, BUT I just walked to our wind tunnel at university, and stood in it. It takes no effort to stay upright up to 50km/h. At 80km/h one has to concentrate on staying upright, didn't go faster than that.

      --
      # ssh -l neo the_matrix; killall -9 agent_smith
    2. Re:You know... by PhysicsExpert · · Score: 3, Interesting

      I think you'd actually lose your balance as the friction force would act on your feet whereas the drag force would act on your whole body. Anyway at what speed would the two forces be equal?

      drag = 0.5*C*A*D*V^2
      where:
      C is the drag coefficient
      A is the cross section area
      D is the density of air
      V is the velocity


      The frictional force will equal FMg
      Where:
      F is the coefficient of friction between the walkway and the shoes of the person
      M is the mass of the person
      g is acceleration due to gravity


      Anyway using C = 1, A = 1.4m^2, D = 1.3KgM-3, F = 1, M = 70kg the forces will balance at about 23ms-1 or 51mph

      --
      All that glitters has a high refractive index.
    3. Re:You know... by Funkitup · · Score: 4, Interesting

      All the people on the belt should pull enough air along with them so air pumps wont be that necessary.

      A basic invention is not dissimilar to a train - you get into a box that has rollers/wheels on the bottom. Internal friction in the wheels/rollers will accelerate the box on the conveyor belt and the box can then be accelerated to whatever speed wanted (extremely fast if in a vacuum). The same effect will slow the box down when it comes off the other end.

      Boxes can then be sent back using a travellator that goes the other way, or another idea is to make them collapsible so they can go back under the conveyorbelt.

  2. Transition by The+Only+Druid · · Score: 4, Interesting

    As mentioned in the article, the most difficult issue is the transition from moving on the walkway and moving on stationary ground.

    It seems to me the best solution to this is to have "lanes" in the walkway. The far left lane would move at the maximum speed, whereas successive lanes to the right would be decelerated. When exits were reached, you could easily step to the right to get to a lower speed; the transition between 9km/h and 6km/h is still a transition, but its less than 9km/h to 0km/h.

    --
    "Stumble before you crawl"
    1. Re:Transition by lfourrier · · Score: 3, Interesting

      Already done, already in Paris, during 1900 universal exposition: a two lanes, two speeds walkway
      http://gallica.bnf.fr/scripts/Consultatio nTout.exe ?O=03300029&E=50

    2. Re:Transition by Anonymous Coward · · Score: 5, Interesting
      An easier way to do this woul be to do what they've done recently in Japan to solve this issue. They've got sliding panels as the tread that propels you. Toward the beginning and the end, the panels slide over each other, which slows down the railway. This is because each section of the railway lets a certain number of these sliding panels through per minute, but as they panels lap over each other, the speed needed to let the same number of panels through decreases. This is probably tricky to visualize.

      In the middle of the runway, the panels look like this (different numbers to indicate the different individual panels)

      11111111111________22222222222________33333333333
      ________22222222222________33333333333________4444 4444444

      (sorry about the multiple _s...I've never had to try and find an alternative for on /. before)
      At the ends, they slide together like this:

      111111111112222222222233333333333
      222222222223333333333344444444444

      So that even though the speed slows down, the panels don't squish each other, breaking the machine. I saw it on TV, and the dude was just whipping along the corridor. If they combined this system at a higher pace with the roller system they've got in France, they could probably take the speed up a fair bit.

    3. Re:Transition by DeusExLibris · · Score: 3, Interesting

      It seems to me that a better solution would be to have rotating disks at transistion points along the route. This way people could step onto the outer edge of the disk (where the outer angular velocity equals the linear velocity of the belt). They could walk into the center (where the angular velocity is much lower) and then step off into the center hole.

      Of course, the problem with this is that the disk would need to be enormously large to make the centripetal force reasonable.

      A quick calculation shows that acceleration on the outer edge of a 1000m radius disk that has a angular velocity of 100km/hr is ~130m/s^2. Unfortunately, that is ~13g! To get that down to manageable forces, the disk would need to be at least 10K m in radius (13m/s^2 or ~1.4g).

      Since this is just a back of the envelope type of calculation anyway, pehaps someone has a better idea of reducing the forces?

  3. The problem is for distances _under_ 1 km ?! by itsme1234 · · Score: 3, Interesting

    ----
    "The real problem nowadays is how to move crowds; they can travel fast over long distances with the TGV (high-speed train) or airplanes, but not over short distances (under 1km)," he says.
    ---

    How about good ol' walking ?!

  4. Many points of failure? by Savant · · Score: 5, Interesting

    It would seem to me that the sheer number of moving parts in a kilometre or so of walkway must make the chances of frequent failures pretty high compared to other public transport methods. How fault-tolerant is it? Any French Slashdotters able to answer?

    Would be interesting to see some schematics.

  5. Re:The Roads must Roll by GeorgeTheNorge · · Score: 4, Interesting

    Thanks for reminding me of the title.

    What I remember of the story was that they had this rolling road that spanned the USA from east to west, with lanes that went faster and faster. You got on the first slow speed lane, and just walked over to successively faster lanes. The fastest lane was some cool 1950's velocity like 150-300mph.

    Some disgruntled workers clipped a lane or two, with expected results.

    Nice to see Robert Heinlein's idea making it to reality, now if I could only speak Basic with someone on the moon, or have a farm on Ganymede!

    --
    If you got a $100 bill, put your hands up...
  6. it's mechanical.. by way2trivial · · Score: 5, Interesting
    it's a poor solution..
    better would be organic, something like stomach cillia, where the floor doesn't move the length of the journey, but little tiny bits from in place do- not my idea, something I read once.

    the individual elements take turns dropping, moving a tiny bit, pushing up again, and moving you a tiny bit... done repeatedly= ya move down the floor- which doesn't move.

    less to break down, and spilled drinks and food (as long as they aren't too hot) are actually welcome...

    --
    every day http://en.wikipedia.org/wiki/Special:Random
  7. Expressways by ariehk · · Score: 4, Interesting

    As an idea, these expressways are a fairly good way of transporting humans. They travel at constant speed, so there should be no obvious difference to the traveller, no matter what the speed is. Of course, in reailty we'd experience air resistence; try sticking your head out of the window on a car going at 70mph. but there may be some way of reducing this in enclosed tunnels, like blowing air at the same velocity as the floor is moving.

    In Asimov's vision (I think), the different-speed strips were parallel to each other, not serial like this French version. This meant that you's step to the side to go onto a faster strip, and keep going until you hit the fastest one, which could be several hundred miles an hour. As the differential in speed between the strip you are on and those near is never more than about 1mph, you won't do yourself any serious damage by falling over. see diagram:

    ---->---7mph->--
    ---->---8mph->--
    ---->---9mph->--
    etc.

    This structure makes them easier to 'network'. The only danger, I suppose, is if a strip breaks then the speed-differential between it and then next one could be massive.

    I suppose any serious implementation would use some kind of semiconductor thang to decrease friction, and on a wide scale could be very energy efficient. These things are probably more useful to society than a Segway, but you'd have to design a city around them from the ground up, so I doubt they'll change the way we live just yet.

    --
    These people look deep within my soul and assign me a number based on the order in which I joined. -- Homer Simpson
  8. Re:The Roads must Roll by WindBourne · · Score: 3, Interesting

    2 layers. Top layer runs in a circle. The bottom layer looks like our conveyor with hooks to catch the top layer and pull it. It would have to have the capaibility of being pulled back to allow the upper belt to slide incase the conveyor stops.

    How is that idea?

    --
    I prefer the "u" in honour as it seems to be missing these days.