The 2010 ADA Standards for Accessible Design state that side reach range must be no higher than 48 inches and no lower than 15 inches. The side reach requirements apply to operable parts on accessible elements, to elements located on accessible routes, and to elements in accessible rooms and spaces.
People with vision impairments often travel closely along walls which can provide wayfinding cues sometimes called a "shoreline." Objects mounted on walls, partitions, columns, and other elements along circulation paths can pose hazards unless their projection is limited. Those objects with leading edges that are within cane sweep (27" high maximum) or that provide minimum headroom clearance (80" minimum) do not pose hazards and can protrude any amount.
Objects located above elements that are within cane sweep can protrude 4" maximum from the leading edge of such elements provided that any required reach or clear floor space is not obstructed.
Adapted from the United States Access Board and the ADA 2010 Standards for Accessible Design