Lateral Structures (HEC RAS User's Manual)
https://www.hec.usace.army.mil/confluence/rasdocs/rasum/latest/entering-and-editing-geometric-data/lateral-structures-weirs-gated-spillways-culverts-and-diversion-rating-curves
Related Video:
HEC RAS Lesson 8 - HEC RAS Lesson 8 - Geometric Data - Inline Structures
https://youtu.be/XGlSoLlPhes
Related Video:
HEC RAS Lesson 6 - Geometric Data - Entering and Editing Culvert Data
https://youtu.be/Z6hsnSVIlhc