4. Road Construction and Maintenance - continued

Some general principles to consider in ensuring proper drainage from road surfaces are:

• Where possible, use outsloped roads to drain water directly onto forest floor. Note that outsloping may present safety concerns on areas such as sharp curves.
• If roadside drainage ditches are required, drain water from these ditches frequently to avoid flow concentrations.
• Drain water collected along the slope of the backfill for insloped and crowned roads by transporting across the road through culverts or surface cross drains such as water bars (small earthen dams formed in the road to force water off the road surface, out of the side ditches and onto the forest floor) or dips (short road gradient changes or "steps" which check and divert runoff). Waterbars and relief culverts should cross the road bed at an angle of between 30 and 45 degrees in order to provide gradient to the culvert and reduce the maintenance burden (debris will accumulate as the angle approaches a perpendicular alignment to the road).
• The spacing of the road cross drains (culverts, waterbars, dips) depends on the soil type, road gradient and amount of rainfall.
• Avoid placing drainage outlets on fill material since these materials are more readily eroded.
• Direct ditch waters onto undisturbed forest floor to allow water to infiltrate and sediment to settle out. Never drain road side ditches directly into streams.