UK Rail Design Question - Applying More Cant Than The Equilibrium

Hello all

This question is for UK rail designers which I was hoping someone could me with, my question is this, I have:-


o Cen60 Rail (72mm Head width)
o Within a Platform
o 1435 Gauge
o Design Radius of 3255m which gives me an equilibrium cant of  39.862mm.

But I want to apply 50mm of Cant which gives me a Cant Deficiency of -10.138mm.

After looking through the track design manual I could not find anything that states that applying more cant than the equilibrium is invalid.

I know the general rule is 2/3rd of the equilibrium cant is applied and 1/3 is deficient, however what would the negative affects be if we applied more cant than the equilibrium.

If you can help then that would be great.

Thank you.

Parents
  • Stewart, the question is really why do you want to apply excess cant?  I agree with jpln that your lower rail will be subject to excessive wear.

    Neville du Plessis

    Rail Design

    Answer Verified By: Stewart Souten 

  • Hi Neville

    It is not out of choice, the current cant is currently running at approx. 50mm and I cannot reduce it because the track is in a platform and the current clearances are very bad already.

    Other than what JPLN has mentioned is there any other technical reason as to why applying excessive cant would be bad?

    Looking through the track design manual I am unable to find anything that states that applying more than the equilibrium is invalid.

    The only issue that comes to mind would be the rate of change of cant deficiency which I think still works out to be about 38mm/s based on the curvature diagram below:-

    Any thoughts Neville?

    Thanks

Reply
  • Hi Neville

    It is not out of choice, the current cant is currently running at approx. 50mm and I cannot reduce it because the track is in a platform and the current clearances are very bad already.

    Other than what JPLN has mentioned is there any other technical reason as to why applying excessive cant would be bad?

    Looking through the track design manual I am unable to find anything that states that applying more than the equilibrium is invalid.

    The only issue that comes to mind would be the rate of change of cant deficiency which I think still works out to be about 38mm/s based on the curvature diagram below:-

    Any thoughts Neville?

    Thanks

Children
  • Stewart,  Track Design Handbook Sheet B.2.1. (Dec 1999) says that "Cant Excess at normal operating speed of the slowest trains on the curve when running under clear signals" shall not exceed 110mm.  Which means that you must establish the slowest train equilibrium cant first and the excess cannot be >110mm (which seems rather high to me).  That's my opinion, but it is best that you speak to someone with local knowledge.

    Neville du Plessis

    Rail Design

  • Hi Neville

     

    At 65mph with a radius of 3255m i get an equilibrium cant of 40mm, if i apply 50mm of cant then I get 10mm excess.

     

    You mentioned "...you must establish the slowest train equilibrium cant first and the excess cannot be >110mm (which seems rather high to me). "

     

    If I use 5mph (assuming 5mph is the slowest train speeds) with a radius of 3255m I get an equilibrium cant of 0.23634mm, if I apply 50mm of cant then I get 49.76366mm of excess cant.

    Have i misunderstood ??