T=R·tan(Δ/2),L=R·Δ,E=R(sec Δ/2 −1),M=R(1−cos Δ/2)。
T=R·tan(Δ/2),L=R·Δ,E=R(sec Δ/2 −1),M=R(1−cos Δ/2)。
| Item | Formula / Note | Source / Standard |
|---|---|---|
| Curve elements | T = R·tan(Δ/2), L = R·Δ(rad), E = R·[sec(Δ/2) − 1] | JTG D20-2017 Design Specification for Highway Alignment |
| Deflection-angle layout | Deflection per station δi = l ÷ (2R) converted to degrees | Classic curve-setting method |
| Minimum radius | Rmin = V² ÷ [127(f + i)] with side-friction f and superelevation i | JTG D20-2017 Chapter 7 |
| Chord length | C = 2R·sin(Δ/2); arc-chord difference grows with central angle | Geometric relations |