X02.2.1 General.
Where provided, public sidewalks shall comply with the requirements
of this section.
X02.2.2 Wall mounted objects.
Objects with leading edges more than 27 inches (685mm) from the ground and
not more than 80 inches (2030mm) above the ground shall protrude no more
than 4 inches (100mm) maximum horizontally into the public sidewalk.
EXCEPTION: Handrails serving stairs and ramps shall protrude no more than 41/2 inches (115mm) maximum from the wall.
Wall-mounted object dimensioned to a maximum projection of four inches.
Advisory: For elements that do not require knee room below, the designer should consider placing the leading edge at or below 15 inches (380mm) in order to accommodate a greater variety of users.
Discussion: The three principal cane techniques are: 1) the touch technique, where the cane is arced from side-to-side and touches the ground at points outside both shoulders; 2) the constant contact technique, where the cane is slid from side-to-side in a path extending just beyond both shoulders; and 3) the diagonal technique, where the cane is held in a stationary position diagonally across the body with the tip just above the ground at a point outside one shoulder and the handle extended to a point outside the other shoulder. When one of these techniques is used and the element is in the detectable range, it gives a person of average adult stature, who uses proficient technique with a long cane, sufficient time to detect the element with the cane before there is body contact. The typical cane techniques do not locate objects extending into the travel path above the hips. Pedestrians who are blind or visually impaired may travel on any part of the public sidewalk and are not limited to the pedestrian access route.
Pilot research (Karnes et al.) indicates that numerous body contacts are likely to be made with objects that protrude four inches from walls or twelve inches from a post or pylon, even by adults who travel using a long cane proficiently in one of the three principal cane techniques. For persons of short stature, including children, simple geometry indicates that they will be unlikely to detect objects with a long cane before contacting them with the body when the leading edge is as high as 27 inches above the floor or ground. Many persons do not consistently use proficient techniques with a long cane; they are particularly at risk.
X02.2.3 Post-mounted objects.
Freestanding objects mounted on posts or pylons shall overhang a maximum of
4 inches (100mm) when located more than 27 inches (685mm) from the ground
and less than 80 inches (2030mm) above the floor or ground. Where a sign or
other obstruction is mounted between posts or pylons and the clear distance
between the posts or pylons is greater than 12 inches (305mm), there shall
be a bar or similarly detectable element 15 inches (380mm) above the floor
or ground connecting the two posts or pylons. Such bar or other element
shall provide visual contrast with the ground surface.
Post-mounted object seen in elevation, dimensioned to indicate 4" maximum protrusion.
Elevation view of a sign mounted between two posts, less than 80" above grade, with a cane detection bar at 15" above grade. Contrasting finish on bar is indicated.
Discussion: Persons who travel with the aid of a long cane are frequently able to use acoustic information to recognize the location of walls. Even when they do not contact walls, they frequently travel parallel to walls, a short distance away - far enough to miss objects that protrude four inches. They are less likely to be aware of and able to use acoustic information to recognize the location of posts or pylons. Thus, they are less likely to avoid posts and pylons unless they contact them with the long cane. Even a small error in body coverage using a long cane is highly likely to lead to body contact with a post or pylon-mounted sign that protrudes as much as 12 inches. Persons who are blind are more likely to have body contact with objects that protrude even four inches from a pole than they are to have body contact with objects that protrude four inches from a wall. Stop signs that are mounted low in the public right-of-way have been particularly noted as problems.
X02.2.4 Reduced Vertical Clearance.
Railings or other barriers shall be provided where the vertical clearance is
less than 80 inches (2030mm) high. The leading edge of such railing or
barrier shall be located no more than 27 inches (685mm) above the floor or
ground.
Advisory: : Designers should consider placing the leading edge of the railing or barrier at or below 15 inches (380mm) in order to accommodate a greater variety of users. Maintenance of trees and other landscape features that might encroach on the vertical clearance must be performed for the entire public sidewalk, not just the pedestrian access route.
Sketch of a barrier preventing a person from running into a vertical clearance less than 80 inches.
Discussion: Where there are wide sidewalks, travelers who are blind may not be able to discern and travel within just the width of the pedestrian access route.
Frontier issue: The committee agreed that elements that protrude into public sidewalks below head height would be more detectable by cane to a broader range of pedestrians with vision impairments if the leading edge were lower than the maximum 27 inches above the ground currently specified in ADAAG. Comments of pedestrians who have vision impairments indicate that projecting elements mounted on walls and/or poles, and railings with their leading edges higher than 15 inches, are not regularly detectable in cane travel by persons of varying stature and travel technique.
However, pedestrians who use wheelchairs require a minimum height of 27 inches above the ground to provide knee room at drinking fountains, telephones, and other pedestrian features that are commonly mounted to project from walls and poles on or along the public sidewalk; in fact, users of larger chairs or electric scooters may require even more height for knee room. The committee believes that there are design solutions to meet these conflicting constraints, and recommends that the Access Board continue to work on this issue.