Euler Spiral
Also known as clothoids, spiros or Cornu spirals
They are curves whose curvature changes linearly with curve length (curvature of
a circular circle is the reciprocal of it's radius)
eg: Railway tracks where the curve changes into a straight track
Derived using Fresnel Integrals
Usages
Track Transition Curves
Used in Optics to describe diffraction patterns
Rollercoaster clothoids
Velodromes (bicycle curves) - for rapid entry and gradual exit