A typical one-lane secondary road. The widened shoulder on the left provides room to allow opposing traffic to pass.Many forestry roads are built to secondary road specifications, especially in forest blocks in the 1,000 to 15,000 ha range. They are unsealed, permanent one or two-lane roads constructed to a high standard.
They generally:
- Carry between 20 and 80 heavy vehicles per day or between 60,000 to 250,000 tonnes per year
- On flat and rolling terrain, have a road width of 7-8 m, desirable maximum adverse grades of 10% or 12% for short distances, and are designed for a speed of 50 km/hr
- On mountainous terrain, have a road width of 6-7 m, are designed for a speed of 40 km/hr, and desirable maximum adverse grades of 12% or 14% for short distances.
However, the road width is commonly reduced to 4.5-5 m, to reduce construction costs. In this case, full-width sections are required at regular intervals to allow opposing traffic to pass. Consider keeping road grades for 50 Max and HPMV trucks to 12.5% adverse loaded for all terrain unless the road surface is designed for these units. Also, incorporate more width on corners for off-tracking 50 Max and HPMV than for standard 4 axle trailer units.