# Turnout with Curved Switches

The following formulae are used for the calculation of turnouts with curved switches

where R is the radius of the outer lead rail, G is the gauge, h is the lead of the straight leg of the crossing ahead of TNC up to the TP of the lead curve, t is the thickness of the switch at the toe, I is the distance from the toe of the switch to the point where the tangent drawn to the extended lead curve is parallel to the main line gauge face, V is the distance between the main line gauge face and the tangent drawn to the lead curve from a distance l from the toe, y is the vertical ordinate along the 7-axis, a is the crossing angle, and b is the switch angle.