Curve Radius Question

Inkaneer Oct 17, 2019

  1. mtntrainman

    mtntrainman TrainBoard Supporter

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    OH Oh...pick me!! Pick me !!!

    I remember this subject from years back.Superelevation is based on max track speed. In the US...I found some information for 1:1 US railroads that run both freight and passenger trains online and bookmarked it....

    Normally, passenger trains run above the balancing speed, and the difference between the balancing superelevation for the speed and curvature and the actual superelevation on the curve is known as unbalanced superelevation. Track superelevation is usually limited to 6 inches (150 mm), and is often lower on routes with slow heavy freight trains in order to reduce wear on the inner rail. Track unbalanced superelevation in the U.S. is restricted to 3 inches (76 mm), though 6 inches (152 mm) is permissible by waiver. There is no hard maximum set for European railways, some of which have curves with over 11 inches (280 mm) of unbalanced superelevation to permit high-speed transportation.[8]

    The allowed unbalanced superelevation will cause trains to run with normal flange contact. The points of wheel-rail contact are influenced by the tire profile of the wheels. Allowance has to be made for the different speeds of trains. Slower trains will tend to make flange contact with the inner rail on curves, while faster trains will tend to ride outwards and make contact with the outer rail. Either contact causes wear and tear and may lead to derailment if speeds and superelevation are not within the permitted limits. Many high-speed lines do not permit the use of slower freight trains, particularly with heavier axle loads. In some cases, the wear or friction of flange contact on curves is reduced by the use of flange lubrication.
     
    Last edited: Oct 20, 2019
  2. DCESharkman

    DCESharkman TrainBoard Member

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    So what would happen if you ran a train on a super-elevated track in outer space? Would the cars just float off?

    This was a question from my daughter..........

    I did a very modest elevation of my track on my layout. This was not using the Kato track. It does have a nice look and I have not seen any issues with it.
     
    mtntrainman likes this.
  3. acptulsa

    acptulsa TrainBoard Member

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    Sounds like a good moment to teach some physics.

    No, if the curve is superelevated enough, a train in space will track right through it. It won't float away until it reaches the straight track!
     
  4. NtheBasement

    NtheBasement TrainBoard Member

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    Yes, I stand corrected.
     
  5. DCESharkman

    DCESharkman TrainBoard Member

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    The correct answer would be that they would peel off over the inside rail due to centripetal acceleration towards the center of the curvature.
     
  6. acptulsa

    acptulsa TrainBoard Member

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    If the superelevation is 90°, there is no inside rail.
     

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