Forest Road Engineering Guidebook - Ministry of Forests

Table 2. Summary of alignment controls for forest roads.
Minimum
Minimum
Passing
Stopping Sight Minimum Suggested Maximum Road Gradientb,c Stabilized Design Sight Distance Radius of
Road Speed Distancea for 2-Lane Curve Favourable Adverse
Width (m) (km/h) (m) Roads (m) (m) S Pd S PeSwitchbacks 4 20 40 15 18% for 12% for
16% distance 9% distance 8%