Tactile Ground Surface Indicator (TGSI)
Tactile Ground Surface Indicator TGSIs also known as detectable warning surfaces or tactile attention indicators. They are standardized walking surfaces that convey information to people with vision loss through texture and occasionally sound. They are typically made from inserts (e.g., metal, rubber, stone or plastic) or can be built directly into ground surfaces made of concrete. Tactile Ground Surface Indicator TGSIs should have a texture that can be felt underfoot and detected by a long cane. Their edges should be beveled to decrease the likelihood of tripping.
There are two types of Tactile Ground Surface Indicator (TGSI):
- Attention TGSIs – sometimes called warning TGSIs, call attention to key hazards such as the start of a staircase or the edge of a platform.
- Guidance TGSIs – also known as wayfinding TGSIs, provide information about the direction of travel through open spaces. They are designed to guide a person on a designated path of travel.
When Tactile Ground Surface Indicator TGSIs are installed as pre-manufactured panels or surface-mounted onto an existing ground or floor surface, the panels should have beveled edges. The base surface of the Tactile Ground Surface Indicator (TGSI) panels should be no more than three millimeters above the existing surface.
Surface-mounted installations are not ideal and should only be considered when cast-in-place or recessed installations can’t be achieved. Tactile Ground Surface Indicator TGSIs should always be attached firmly to prevent edges from lifting.