track transition curve

It must change (ramp) gradually in a track transition curve.

The straights transition to the circular turn through a moderate Track transition curve.

In highway and railroad design, a tangent is a straight section of road or track; see track transition curve.

A track transition curve, or spiral easement, is a mathematically calculated curve on a section of highway, or railroad track, where a straight section changes into a curve.

He developed an empirical method of setting out track transition curves and introduced an alternative design to the helicoidal skew arch bridge at Rewe and Cowley Bridge Junction, near Exeter.

This involves the layout of three main track types: tangent track (straight line), curved track, and track transition curve (also called transition spiral or spiral) which connects between a tangent and a curved track.