Bridges/Culverts (HEC RAS Mapper User's Manual)
https://www.hec.usace.army.mil/confluence/rasdocs/rmum/6.6/geometry-data/bridges-culverts
Inline Structures (HEC RAS Mapper User's Manual)
https://www.hec.usace.army.mil/confluence/rasdocs/rmum/6.6/geometry-data/inline-structures
Lateral Structures (HEC RAS Mapper User's Manual)
https://www.hec.usace.army.mil/confluence/rasdocs/rmum/6.6/geometry-data/lateral-structures
Related Lessons:
HEC RAS Lesson 5 - Geometric Data - Entering and Editing Bridge Data
https://youtu.be/gmpqN_hKcRc
HEC RAS Lesson 8 - Geometric Data - Inline Structures
https://youtu.be/XGlSoLlPhes
HEC RAS Lesson 9 - Geometric Data - Lateral Structures
https://youtu.be/wwzZobVDLic