But when walking alongside projecting objects, they cannot detect overhangs because proper cane techniques and guide dogs keep persons away from the edges of a path from walls. A slight overhang of not more than 100mm rarely hazardous. A flight of stairs shall have uniform riser heights and thread depth and the riser should not be more than 180mm high. The thresd should not be more than 280mm deep. Stair handrails shall be installed on both sides and have thir tops betwen 800mm and 920mm from their nosing.
Many disabled persons rely upon handrails to maintain balance and prevent serious falls.
Handrail extension at the top and bottom of stairs provide tactile cues for persons with visual impairments and the continuos handrail will assist them in negtiating stairs and changes in direction. Handrail extension should not project into another path of travel and handrails should return to the wall, floor or post so as not to constitute a hazard. The handrail must be designed to be easily grasped and to provide a firm and comfortable grip do that the hand can slide along the rail without obstruction. The circular section should have a diameter of not more than 40mm. An upper case X should be used for character measurement.