Q: What is Tactile Ground Surface Indicator (TGSI)?

A: Tactile Ground Surface Indicators are a detectable warning system for the vision impaired. Two types of Tactile Ground Surface Indicators exist each serving a different purpose. The common raised dots seen around the city streets is referred as Hazard TGSI (or Stop TGSI), as shown in Fig. 1a. The other type of TGSI is referred as Directional TGSI, its physical appearance is as shown in Fig 1b. The two combined serves the purpose of guiding the vision impaired in a terrain where potential tripping hazard may occur.

Q: Why is Tactile Ground Surface Indicator necessary?

A: Quoting:

http://www.humanrights.gov.au/disability_rights/dda_guide/dda_guide.htm

 “The Federal Disability Discrimination Act 1992 (D.D.A.) provides protection for everyone in Australia against discrimination based on disability. It encourages everyone to be involved in implementing the Act and to share in the overall benefits to the community and the economy that flow from participation by the widest range of people.”

TGSI forms part of this DDA.

Q:  What are Tactile Ground Surface Indicators made from?

A: The relevant Australian Standard AS/NZS 1428.4 2002 specifies the dimension of the TGSI profile and how these TGSI should be laid. The Standard also indicates a luminance differential between the TGSI and its surroundings and slip resistance rating; there is however, no restriction as to what material the TGSI should be made of.

A large range of TGSI is currently available in the market; these include Ceramic, Polymer Concrete, Rubber, Plastic, Brass, Stainless Steel, Composite Cork, Acrylic, Natural Stone, Reconstituted Stone and Concrete to accommodate a variety of substrates that requires them; including concrete, asphalt,  ceramic tile, carpet tiles, carpet, vitrified tile, glass, granite, travitine, brick, epoxy, limestone, sandstone, paver, slate tile, steel, timber, parquetry, vitrified porcelain, vinyl and masonry.

Furthermore, a variety of installation methods are available from various vendors. These products all have their strengths and weaknesses as well as varying degrees of aesthetic appearances. Choosing one that suits your particular need would require an understanding of the installation mechanism and the compatibility with the substrate that it applies to; discussing with an expert in the industry prior to a decision would save a lot of headache later.

Q:  What guarantee should I expect from the TGSI manufacturers?

 
A:   There are two areas where TGSI users should concentrate on, firstly the material itself and secondly the workmanship of the installation; both can lead to the failing of the TGSI.

The Standard stipulates the following material requirements:

More importantly, the workmanship on the installation has a greater influence on the final product itself. Here are some common problems on TGSI products:

 
Dr. Michael Lim from Eigen has prepared an article on this subject, interested readers would be able to deduce from the facts presented there and make sound decisions first hand. Dr. Michael Lim was an experienced CSIRO research scientist specializing in Thermodynamics of Oxide and Alloy materials.