Seattle’s Bicycle and Pedestrian Coordinator administers a citizen-request improvement program to receive, prioritize, and address right-of-way problems. The process helps the city defend liability claims by documenting its response to safety and maintenance concerns.

ADAAG Appendix: A4.4.1
(Protruding Objects).
Service animals are trained to recognize and avoid hazards. However, most people with severe impairments of vision use the long cane as an aid to mobility. The two principal cane techniques are the touch technique, where the cane arcs from side to side and touches points outside both shoulders; and the diagonal technique, where the cane is held in a stationary position diagonally across the body with the cane tip touching or just above the ground at a point outside one shoulder and the handle or grip extending to a point outside the other shoulder. The touch technique is used primarily in uncontrolled areas, while the diagonal technique is used primarily in certain limited, controlled, and familiar environments. Cane users are often trained to use both techniques.

Australian guidelines prohibit the placement of any obstruction within the sidewalk 'walk zone', a 60-inch-wide pedestrian route between intersections.

Protruding Objects

critical zone is between 27" (685 mm)and 80" (2030 mm) above finished floor (AFF)

maximum projection perpendicular to circulation route:
— 4" (100 mm) maximum
projection from wall
— 12" (305 mm) maximum projection from post (if detectable at base)

ADAAG 4.4.2 Head Room.
Walks, halls, corridors, passageways, aisles, or other circulation spaces shall have 80 in (2030 mm) minimum clear head room. [...]