Annex C & D
Root protection area methodology
Calculation rules
Single stemRPA radius = 12 × stem diameter at 1.5 m
2–5 stemsEffective Ø = √(d₁² + d₂² + … + dₙ²)
More than 5 stemsEffective Ø = √(mean stem ز × number of stems)
CapRadius limited to 15 m (≈ 707 m²) per Annex D
RPA area = π × r². Where site conditions justify it, the circular RPA may be offset to a polygon of equal area (para. 4.6.2).
Quick calculator
Effective Ø
587 mm
RPA radius
7.04 m
RPA area
155.7 m²