Turnout on a spiral

Hi Friends

I have a question about designing turnouts on an spiral / transition curve with cant applied.

We have a case where we need to replace 2 turnouts and a connection, with 2 new turnouts and a connection. We can't move the turnouts location or change the design of the maintracks so we can't place the turnouts in a curve or on straight track.

It looks like the attached file with a grayscaled map behind. It is the turnout 05a and 05b we have problems with.

The Curve (red line) is radii 800 m with a cant of 125 and 140. Length of the transition curve (blue line) is 85 and 95 m. Green line is straight track.

One problem is that the transition curve has an different radii throughout the length of it - So what is the radii of the turnout foot?

And when we have 2 turnouts with one bench inside and another outside - how can we calculate the connection between these?

In BRT we can place the turnout on the spiral, but we cant use the Create Connection function. If we use the Connection Editor can we then trust the result?

Do anyone have any experience with the same problem we have? Please share.

Kind Regards

Martin Laursen

MANL@ramboll.com

Phone: +45 5161 7749