Surveying and Transportation Engineering · Lesson 21 of 27

Spiral Transition Curves

A deep dive into the transition or Euler spiral that eases a vehicle from a straight tangent onto a circular arc, covering the linear-curvature law, the spiral angle theta_s = Ls / (2R), tangent offsets with the one-third deflection rule, the shift p, and the three length criteria (comfort by Shortt, superelevation runoff, and the empirical minimum) worked through to full stationing.

15 min read · Super Ea