FSH 7709.56 - ROAD PRECONSTRUCTION HANDBOOK
10/85 R1 SUPPLEMENT 1
4.84 - Inslope, Outslope, and Crown. Outsloping should be limited to areas with erosion
resistant soils and to those areas where road grade is less than 8 percent. Incorporate grade
reversals or dips in the design to ensure positive drainage of outslope roads.
Roads should not be outlsloped where winter haul is anticipated.
Generally, positive drainage is not achieved by outsloping unless the percent of outsloping
exceeds the road grade by 1 percent. Outslopping is more effective on flatter grades in the range
of 0 to 4 percent. Water coming over the cutbank will tend to cut its own ditch on steeper
outsloped roads because the water will have a greater tendency to run along the inside edge of
the road than to flow across the road.