Free Standing Over Hanging Objects

4.4.2 Head Room. Walks, halls, corridors,
passageways, aisles, or other circulation
spaces shall have 80 in (2030 mm) minimum
clear head room (see Fig. 8(a)). If vertical
clearance of an area adjoining an accessible
route is reduced to less than 80 in (nominal
dimension), a barrier to warn blind or
visually-impaired persons shall be provided
(see Fig. 8(c-1)).

ADA ACCESSIBILITY GUIDELINES FOR BUILDINGS

Legend or Graphic Conventions

Stair Tread Lines For The Blind