Safety and Liveability for the Visually-impaired and the Blind
> More than a quarter of million Canadians have some degree of visual impairment; approximately 20% of these are totally blind. More than a million Canadians, mostly men, have some sort of colour blindness, most commonly to red, blue or gray. The incidence of impairment increases with age: an 80 year-old needs 3 times the light of a 20 year-old. There are different kinds of visual disability: darkness, blurring, peripheral or tunnel vision, spots in the visual field. The real need is for clues for orientation and direction; the design response must be distinctive, consistent and simple. Pair non-visual cues such as sound, feel, air movement, resiliency, smell and temperature with visual cues such as light, colour or tonal contrast and texture. Sound clues can include elevators, motors, running water and fans. Glare and patterning can confuse people with partial vision. If possible, consult with known users for advice.
- Provide a change of material/ texture/ colours / tonality at transitions in elevation, at road hazards, stair risers, runs, nosings and landings. The CNIB recommends a minimum 70% colour contrast [B1 - B2 X 100 / B1, where B1 is the reflectance of the brighter colour and B2 is the reflectance of the
darker colour]. Avoid flooring materials that glare.
- At curb ramps in sidewalks, provide a textured, detectable surface
In the images to the left, bumps and lines that are cane-detectable help to guide blind people around obstructions and to the doors in the Ottawa Convention Centre and in an office bulding in Kyoto, Japan. In the image above, a sidewalk incorporates textured brick to warn of a driveway in St. Petersburg, Florida
- Detectable warning surfaces must be consistent throughout the development: use heavier textures to indicate hazards and lighter textures for guides. Ensure that these surfaces cannot be confused with other flooring surfaces. An 'environmental shoreline' can be created by changing the whole surface to define a walkway (for example, use carpet for a sitting area, then use linoleum at a walkway that snakes through the sitting area)
- Eliminate overhead hazards (provide minimum headroom of 1980mm). Protect objects that protrude more than 100mm from walls with wing-walls or railings (a recess is preferable). Don't overhang low building elements such as bays over walkways (for instance, put planting under the bay). Hazards must be cane-detectable
- Walkways should be a minimum of 1500mm wide for cane sweep
- Knurled door-opening handles have been used to indicate hazardous areas (BC Building Code) or exits (ANSI Code). Check with your local support services for advice
- Avoid large expanses of clear, unmarked or undivided glass at the main entry, including the doors
- Provide lighting "hot spots" at critical areas & control devices (such as at elevator), minimum 100 lx (200 lx preferred). Choose surfaces that don't glare.
- At entry control devices and other locations provide braille instructions and / or tactile plans of the building
In the image to the right is of a sign at the Tokyo JNR Station. Raised lines and Braille explain the layout of public washrooms.
- Avoid the use of heavy patterns on floors and large plate mirrors on walls
- Guards at doors, drops etc. must be 'cane detectable' i.e. there must be a bottom rail no higher than 400mm/ 16"
- Provide magnifier peep holes at suite entrances in apartment buildings
- Provide signage that has raised raised sans-sarif print (plus grade 2 Braille if possible), at eye level: a consistent location 1350mm above floor at either right side or handle side of door. Colour contrast a minimum of 70% between letters and background.
- Incorporate a speaking device to announce floor level and direction of movement in elevators. Use simple, raised print as well as grade 2 Braille at buttons, door jambs etc.
- A transistor radio-based technology referred to as "talking signs" can be used to direct blind people through the building or around hazards
- Place fire alarms in public areas above the exit doors
- Put in more electrical plugs so as to eliminate the need for extension cords, help to minimize tripping hazards
- Colour can assist in orientation within the building. Colour contrast exit doors (from walls), using same colour for all exit doors. Emergency equipment should be a consistent colour.
- Tactile clues can assist in orientation within the building, indicating different types of space. Avoid surfaces with sharp bumps that could tear skin
- Provide colour contrast at handrails against walls in stairways