Inputs
km/h
m
m
about edge
cross-slope (e.g. 0.02)
max relative gradient (Δ slope)
Method & assumptions
- Required superelevation: e + f = V²/(127·R) (metric: V km/h, R m) → V²/(15·R) imperial (V mph, R ft).
- Side friction f from AASHTO design-speed curve (approx interpolation built-in).
- If e > emax, use e = emax and report shortfall.
- Runoff length: Lr = (n·w·e)/bn·bw simplified; bn = max relative gradient (~0.5%/lane @ 80 km/h).
- Tangent runout: TR = enc/e · Lr.
Results
Side friction f (AASHTO)—
e + f required—
Required e—
Status vs emax—
Min radius Rmin (emax+fmax)—
Superelevation Runoff Lr—
Tangent Runout TR—