4.7.8 Superelevation Transition Type

Linear or reverse parabolic transitions may be used for attaining superelevation.
Where appearance is a factor (e.g., curbed sections and retaining walls) use of reverse parabolic is recommended.
 This produces an outer edge profile that is smooth, undistorted, and pleasing in appearance. However,
for bridges, linear transitions are generally preferred
 for constructability, ride quality, and lower cost.
Notate the transition type in the plans to ensure the transition is properly constructed.
Figure 4-2
shows reverse parabolic and linear transitions over the full length of the transition. Refer to
AASHTO's A Policy on Geometric Design of Highways and Streets
for alternative methods for developing smooth-edge profiles over the length of the transition.