Pavement cross slope and grade:[5] Cross slope is the extent to which the cross-section of a road resembles an upturned U. Higher cross slopes allow water to drain more easily. Grade is the steepness of the road at a particular point, which affects both drainage and force exerted by the vehicle on the road. Vehicles are less likely to aquaplane while traveling uphill, and far more likely to do so at the trough of two connected hills where water tends to pool.