(for more information refer to AS1428.4)
What are Tactile Ground Surface Indicators (TGSI)?
TGSI’s are part of a global initiative to provide greater access for people in the built environment. For over 30 years, TGSI’s have proven a dignified and non-discriminatory means of providing unassisted mobility to the visually impaired.
Tactile Ground Surface Indicators are series of organised raised dots and bars that are installed on pedestrian surfaces to assist in the orientation of people who are blind or vision impaired. TGSIs are primarily designed to give tactile warning to people so that they may safely negotiate the built environment. Felt underfoot, detected by cane, or even read as a light contrast between a surface and a hazard, TGSIs give information to the vision impaired on where they are, where they are going and where they have been. TGSIs come in two main types:
* Warning – Dots
* Directional – Bars
They can be constructed in two ways. As discrete TGSIs – dots or bars made of one or two materials that are individually affixed to a substrate/surface; or as integrated TGSIs – dots or bars made of the same material and integrated as one consistent mass.
Why has the placement of TGSI become mandatory?
In Australia the following legislated codes and standards are very specific to the design, installation and placement of TGSIs. These standards are enforced to allow for the clear reading of TGSIs in all public spaces and to ensure that the experience of the vision impaired remains consistent in the urban landscape:
- Australian and New Zealand Standards AS/NZS 1428.4.2009 – this standard states how to do it (TGSI design/layout/application)
- The Building Code of Australia (BCA) Section D Clause 3.8 – this document states what must be done as a legal minimum (State/ National Building Certification requirements for new work).
- The Disability Discrimination Act (DDA) – this Federal Act states why and within what context (legal rights of individuals preclude and can override standards or state legislation, even those of a regulatory body).
What is Vision Impairment ?
For those of us who may experience future vision impairment – and it’s an alarming percentage of the aging who are affected – there are a host of problems that might afflict us, the effects of which are summed up as follows:
❚ Cataracts: these may affect all or irregular portions of the visual field and cause an image to be seriously distorted.
❚ Diabetic retinopathy: this causes poor contrast between objects and fluctuating light levels are a serious problem – the quality of vision can also fluctuate from day to day.
❚ Tunnel vision caused by glaucoma: this restricts vision to a narrow circle and is worsened by low or fluctuating light levels.
❚ Tunnel vision retinitis pigmentosa: objects and pedestrians suddenly appear in the path of travel – naturally, crowded areas are difficult to negotiate, and central vision may also be obscured.
❚ Central vision loss caused by age-related macular degeneration: damage to the central field of vision and details are hard to see – colours may be difficult to distinguish.
❚ Cortical field defects – homonymous hemianopia: this is not a problem with the eyes, but with the brain; strokes and brain injuries are the common causes and, again, suddenly appearing objects and individuals are a problem and
❚ Colour deficiency, otherwise known as the “tomato factor”: one in 10 males and one in 200 females in Australia have a colour deficiency (colour blindness), or what is known as the ‘tomato factor’ – major problems with the colours that a tomato passes through when ripening; i.e. green, olive green, orange, yellow, pink and red. And for many more the common problems are depth perception, head high objects, fluctuating light, unexpected drop-offs and poor contrast. Most people have had to come to terms with these conditions – at least occasionally, after a sharp shock to the head.
Where should TGSI be used?
- Where ever the public has access to a building or area.
- A platform where any rail, tram, bus or ferry stops.
- At the bottom and top of step(s), stairs, escalators, travelators, ramps, curb ramps, cross paths, etc.
- Around any overhead impediment or hazard other than a doorway with less than a 2 metre clearance in an accessible open public space eg. Fire hose reels, drinking fountains.
- Water bodies or other item or feature of significant risk eg. Paved or built river embankments, rail/tram level crossings.
- Placement of all TGSI must be in compliance with AS1428.4:2009 and should not be proliferated unnecessarily.
Can I see Pathtek’s TGSI before ordering?
Simply telephone or email us and we are happy to show you samples of our product.