Horizontal Curve Design & Check

Highway horizontal curve using e + f = V²/(127·R). Units: V in km/h, R in m, e in %, f dimensionless.

1. Mode & Basic Data

Choose whether to check an existing curve or design a minimum radius for given speed and superelevation.
Posted / design speed to check.
Measured / design radius of the circular curve.
Actual superelevation on the curve in percent.
Design speed to be used for the new curve.
Target superelevation on the curve (must be ≤ emax).

2. Friction & Limits

Working friction used to size e (typ. 0.08–0.12).
Upper limit on friction demand, for safety/comfort.
Code limit (e.g. 7–10%). Applies to both modes.

Formula used: e + f = V² / (127 · R) (V in km/h, R in m, e and f dimensionless). Superelevations entered in percent are converted to ratios internally.