Protruding objects – From Designing Sidewalks and Trails for Access – Part II of II: Best Practices Design Guide. Section 4.1.3
Objects that protrude into the sidewalk corridor but are higher than 2.03 m (80 in) are not a problem for people with vision impairments because most pedestrians require less than 2.03 m (80 in) of headroom. In addition, people with vision impairments who use long white canes to navigate (if they are of adult stature and using their canes skillfully) will usually detect and avoid objects on the sidewalk that extend below 685 mm (27 in). However, obstacles that protrude into the sidewalk between 685 mm (27 in) and 2.03 m (80 in) and do not extend to the ground, are more difficult to avoid because the long white cane is unlikely to contact the object before the person contacts the object. Guide dogs take their owners around obstacles.
|POTENTIAL PROBLEM: This pedestrian who is blind is approaching the telephone kiosk from the side. When obstacles mounted on posts can be approached from the side they should not protrude more than 101mm (4 in). This pedestrian does not detect the obstacle, which could cause him to collide with the obstacle.|
|This pedestrian who is blind is able to avoid colliding with this telephone kiosk because he detects the pole with a cane before coming in contact with the phone. Pole mounted objects that can only be approached from the front should not protrude more than 305 mm (12 in) into the sidewalk corridor.
Pedestrians with vision impairments often travel close to the building line. According to the Americans with Disabilities Act Accessibility Guidelines (ADAAG) Section 4.4, if an object is mounted on a wall or the side of a building, it should not protrude more than 101 mm (4 in) into the sidewalk corridor (ADAAG 4.4, U.S. Access Board, 1991). If an object is mounted on a post that can only be approached from the front, it can protrude up to 305 mm (12 in) because the angle of the long white cane allows a pedestrian who is blind to identify the post before bumping into the protruding object. However, if the post-mounted object can be approached from the side, it should protrude no more than 101 mm (4 in) into the sidewalk corridor. Signs mounted on two posts should have a crossbar at 305 mm (12 in) above the walking surface so that a pedestrian using a long white cane can readily detect the sign. Stop signs mounted on a single post should be no lower than 2.03 m (80 in) or be placed outside of the paved portion of the sidewalk corridor (e.g., in a planting strip).
The least possible amount of protrusion should be used in each situation. Furthermore, because pedestrians with vision impairments do not always travel in the pedestrian zone, protruding objects should be eliminated from the entire paved portion of the sidewalk corridor. Protruding objects do not need to be eliminated from the planter/furniture zone if it is separated from the sidewalk with a planting strip or other type of setback.
|This pedestrian, who is blind is walking down a sidewalk that contains a number of obstacles that are difficult to detect using a long white cane, because they protrude into the path of travel between 685 mm (27 in) up from ground level and below 2.03 m (80 in) in height.|