Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Built Environment (hierarchy name)
4. Single Built Works (hierarchy name)
5. single built works (built environment)
6. [single built works by specific type]
7. [single built works by function]
8. transportation structures
9. [transportation structures by function]
10. water transportation structures

Anotations

Scope note:

Vertical, often wooden, structures to help align water borne vessels as they approach a lock or a bridge. Guidewalls guide the vessel into the lock chamber or between the piers of the bridge. These also provide a place for the vessels to tie-off while awaiting entry to a lock chamber.