Calculating Tie Lengths in a Curved Switch

A curved switch consists of a diverging branch within a curve in the main line. As the branch separates from the main, the ties need to get longer to accomodate both tracks until they are far enough apart to have separate ties. In this model, the ties are perpendicularly aligned to the main rails. The radius of the diverging curve can be either larger or smaller than the radius of the main curve.

This program calculates the lengths of the ties needed to complete the switch, and the angle and number or the frog needed.

Explanation of Input Boxes

Note: All dimensional units must be the same. Inches, meters, etc.

Radius of Main Line and Radius of Diverging Line

  There are two boxes per. One for the radius and one for an optional
  multiplier. The multiplier can be used to convert feet to inches,
  meters to centimeters, metric to english, or whatever you like. If
  not used, set it to 1.

Normal Tie Length

  The length of a normal track tie. Switch ties will progressively
  get longer.

Tie Spacing

  The measurement from tie to tie, not the gap between them. It is the
  center to center distance. The width of ties is not needed.

Snap to Nearest Unit

  This allows you to select how much precision you need. The tie length
  will be rounded to the nearest unit you select here.

Track Gauge

  This is only needed if you are using the optional frog angle and number
  calculator. Enter the actual gauge-face dimension. The frog angle will
  be calculated in degrees. The frog number is 1/2 the cotangent of 1/2
  the frog angle. Both frog angle and number are rounded to .25.

Calculating Tie Lengths in a Curved Switch

Explanation of Input Boxes

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