Tactile Indicator Luminance Contrast
Tactile Indicator Luminance Contrast Requirements
Discrete TGSIs are tactile indicators that require a minimum of 45% luminance contrast. These are tactiles that consist of individual units, which are installed onto the pedestrian surface one at a time.
Composite TGSI’s are tactile indicators that require a minimum of 60% luminance contrast which are also discrete tactile indicators, however, they are manufactured using two colours or materials.
Integrated TGSIs require a minimum of 30% luminance contrast. These tactiles are a series of tactile indicators that are incorporated on a backing tile that consists of the same material and colour of the tactiles.
Stair nosing and edging are required to have a contrast strip not less than 50 mm and not more than 75 mm deep across the full width of the path of travel with 30% contrast to the tread background.
Why do tactile indicators and stair nosings require luminance contast?
Tactile Ground Surface Indicators (TGSI’s) are designed to assist pedestrians with vision impairment to navigate the urban environment safely through visual and sensory stimulus. Generally, people with low vision are able to see colour and differentiate between different colours, however, their ability to discriminate colours may also be impaired. A small percentage of vision impaired persons are completely blind and so, the luminance contrast of walkways and tactile indicators allow for people with low vision to distinguish between surfaces and gather information to detect hazards and safe paths of travel. It is essential that the luminance requirements are met so that the contrast in luminance of tactile indicators relative to that of the surrounding surface are distinguishable to allow for safe navigation.
Below are examples that highlight the importance of luminance contrast between the tactile indicators and substrate. The yellow integrated tactile mats provide a clear distinction between the tactiles and asphalt, allowing people with impaired vision to identify that there is a tactile surface present so that they can determine if a hazard or safe path of travel is present. However, the black integrated tactile mats are very similar in colour to that of the asphalt and provide poor luminance contrast as they both reflect light similarly.
Some other minimum luminance contrast requirements specified in the BCA and Disability (Access to Premises – Buildings) Standards include;
- Accessways – Any obstracles present within an accessway must have 30% contrast to the background surface.
- Signage – Braille signage is required to have a 30% luminance contrast relative to the surface that it is mounted. The tactile characters and symbols on the sign must also have a 30% contrast with the background of the sign itself.
- Glazing – A contrasting strip is required to be at least 75mm wide with a minimum of 30% luminance contrast relative to the floor surface or surfaces within a 2 metre radius. The constrasting glazing strip must extend across the entire width of the glazing panel and located between 900mm and 1000mm above the plane of the floor level.
- Doorways – A minimum width of contrasting area must have a minimum of 30% luminance contrast between the door and frame, door and frame to the wall or door to the wall.
- Lift control buttons – require 30% luminance contrast with the background surface. Alternatively, the button must have a contrasting border around the button that is at least 3mm wide.
- Accessible toilet seats – Minimum of 30% luminance contrast between the toilet seat within Accessible toilet and the floor, pan or wall.