A retaining structure aims at ensuring the stability of subgrade slopes on both sides of culverts or gravity abutments and guiding rivers. Wing walls can be straight (perpendicular to the end wall) or open (open and inclined). The latter, also known as the splayed wall, is the most commonly used form, and the oblique angle is generally 30 degrees. The structural form of wing wall is closely related to topography, fill height and wiring.
Calculation program of culvert splayed wall: /soft/soft_detail.asp? softid=4677