The grade line may be positioned at either edge of traveled way or centerline if multilane. The grade line may be positioned at either the centerline of the median or at the ultimate median edge of traveled way. The former case is appropriate for paved medians 9 m wide or less. The median edges of traveled way of the two roadways are at equal elevation. 204.3 Standards for Grade Table 204.3 shows the maximum grades which shall not be exceeded for the condition indicated.
Steep grades affect truck speeds and overall capacity.
They also cause operational problems at intersections. Properly designed vertical curves should provide adequate sight distance, safety, comfortable driving, good drainage, and pleasing appearance. A parabolic vertical curve is used. Figure 204.4 gives all necessary mathematical relations for computing a vertical curve, either at crests or sags. Since flat vertical curves may develop poor drainage at the level section, adjusting the gutter grade or shortening the vertical curve may overcome any drainage problems.