A steep cross slope provides for proper drainage, while flat cross slopes are amenable to driver safety and comfort. Except in cases of superelevated sections, the cross slope is usually a compromise between the two requirements. The should be consulted for guidance on pavement cross slopes.

Drainage on multi-lane roadways can be enhanced by increasing the cross slope on the outer lanes, or by increasing the cross slope on each successive lane pair. Refer to the for guidance. Drainage on very wide multi-lane roadways such as urban interstates may require special considerations such as porous pavements or transverse trench drains. DES-HYD should be consulted when these considerations arise.

Superelevated transitions should be carefully designed to minimize the extent of flat areas. Flat slopes should not be located in the sag of a vertical curve. It is usually these transition regions where small, shallow ponds of accumulated water, or “birdbaths,” occur. Aggressive drainage techniques such as porous pavement, rough texture, or additional drains must be used to minimize ponding in these “birdbaths.”