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Guide to the ABA Accessibility Standards


This guide explains requirements in the ABA Standards for protruding objects.

Protruding Objects


To prevent hazards to people with vision impairments, the standards limit the projection of objects into circulation paths. These requirements apply to all circulation paths and are not limited to accessible routes. Circulation paths include interior and exterior walks, paths, hallways, courtyards, elevators, platform lifts, ramps, stairways, and landings.

Examples of Protruding Objects

Examples of protruding objects: sconces, handrails, cabinets, drinking fountains and other elements that project into circulation paths).  Notes: These elements must comply with provisions for protruding objects (unless they are located within cane sweep or above headroom clearance).    Requirements for protruding objects apply to all interior and exterior circulation paths of sites.  They are not limited to hallways and corridors and apply equally to circulation paths in rooms and spaces.

Protrusion Limits


People with vision impairments often travel closely along walls which can provide wayfinding cues sometime called a “shoreline.” Objects mounted on walls, partitions, columns, and other elements along circulation paths can pose hazards unless their projection is limited. Those 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.

Limits of Protruding Objects

Wall-mounted objects with leading edges above 27” and less than 80” are limited to a 4” max. projection (4 ½” max. for handrails).  Notes and labels:  Protruding object limits apply to the full width of circulation paths; Objects above headroom clearance can protrude any amount; Protruding objects cannot reduce the minimum width of accessible routes; Objects with leading edges within cane sweep can protrude any amount.

Location Above Detectable Elements

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.

Protruding object located above another with leading edge 27 inches max. AFF.  Note: 4 inches max projection can be measured from the leading edge of fixed elements below objects that are within cane sweep
Pay phone with side partitions with bottom edge 27 inches max. AFF.  Note: Partitions cannot obstruct required clear floor space or protrude into knee and toe space

Side Partitions and Wing Walls

Side partitions or panels and wing walls can also be used to make protruding objects compliant. The bottom edge of panels or partitions must be 27” high maximum.

Recessed Objects

Objects can be recessed in alcoves so that they do not project more than 4” into circulation paths. Alcoves must be sized to accommodate required clear floor space at accessible elements.

Recessed drinking fountain with leading edge above 2 inches AFF
Recessed drinking fountain in plan view projects 4 inches max. from wall surface

Elements, such as wheelchair accessible drinking fountains, must provide a knee clearance of at least 27”. If located to provide, but not exceed this clearance (27” above the floor or ground absolute), they are not protruding objects because the leading edge will be within cane detection.

Hi-lo drinking fountain with higher unit enclosed by lower unit on one site and a wall bump-out on the other

A wheelchair accessible unit located 27” absolute above the ground or floor is cane detectable and can be used to enclose one side of high units for standing access. In this instance, the 27” height is effectively an absolute dimension because it is the minimum required for knee clearance and the maximum specified for cane detection.

Post-Mounted Objects


Free-standing objects with leading edges 27” to 80” high that are mounted on posts or pylons cannot protrude more than 12” into circulation paths. The 12” limit also applies to the clearance between multiple posts (excluding the sloping portions of handrails).

Post-mounted objects with leading edges 27" to 80" high protruding 12" max. from post or pylon; second image shows object on two posts with same protrusion limits and 12" max. distance between posts

Objects with leading edges 27” maximum or above 80” can protrude any amount from posts or pylons.

Images of post-mounted objects that protrude any amount from posts with leading edge 27" max. AFF or 80" min. AFF

Vertical Clearance


Headroom clearance of at least 80” high is required along all circulation paths (except at doors and doorways where a 78” minimum clearance is permitted to accommodate door stops and closers).

Fixed barriers, such as guardrails, are required where the vertical clearance is less than 80” such as at open stairways and along sloped or curved walls. Barriers must have leading edges no higher than 27” so that they are within cane sweep. Fixed planters, benches, and other elements can be used instead of guardrails.

Barriers at Circulation Areas with Reduced Vertical Clearance

Image of vertical clearance less than 80" AFF below stair that is detectable by fixed planter; second image shows railing at point where vertical clearance at curved (or sloped) wall is less than 80."

Reduced Clearance Below Stairway

Clearance Reduced at Curved (or Sloped Walls)

Common Questions

question mark

Are requirements for protruding objects limited to hallways and corridors?

No, requirements for protruding objects apply to all circulation paths, including those in rooms and spaces off corridors. They apply to both interior and exterior circulation paths.

Do drinking fountains pose hazards as protruding objects?

Cantilevered units at standard heights for people who stand must be recessed or protected as protruding objects. This is not required for wheelchair accessible units with no more than a 27” clearance below (the minimum required for knee clearance and the maximum recognized for cane detection).

Can curbs be used to indicate areas with less than 80” of vertical clearance?

The standards specify a maximum height (27”) for the leading edge of barriers so they are within cane sweep, but a minimum height is not specified. Curbs may be mistaken for a step or change in level, instead of a barrier. For this reason, barriers significantly higher than a curb or riser, such as a guardrail, planter box, bench, parapet wall, or similar elements are recommended.

Technical Assistance

Contact the Access Board for guidance on these standards