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Public realm framework
Public Realm Framework - Section 4.2 - Tactile Ground Surface Indicators
Tactile surface ground indicators (TGSIs) are used to assist people with a vision impairment navigate the environment.

Tactile surface ground indicators (TGSIs) are used to assist people with a vision impairment navigate the environment.

There are 2 basic types of TGSI; hazard and directional. TGSIs are required to be used in stairways ramps escalators moving walkways carriageways and to warn of hazards. In a transport setting TGSIs are also deployed at bus/tram stops stations wharves and so on. AS1428.4.1 states:

…in the absence of any indication or warning to the contrary there will be a clear safe continuous path of travel in front of them 2000mm high a minimum of 1200mm in width and a depth of 900mm before the hazardous situation.

One of the most important features of the use of TGSIs is that they should be predictable. For this reason it is important to conform to the relevant Australian Standard. The relevant standard can be confusing as the Australian Standard appendices have multiple scenarios and this often leads to variable implementation. This is especially so at road crossings.

Further confusion can arise as in transport settings the prescribed standard is AS1428.4 whereas in all other settings it is AS1428.4.1. Finally to add another layer of compliance there are 3 main styles of construction of TGSIs and each has a different requirement for achieving a minimum standard of luminance contrast.

Key Design Features

Hazard TGSIs required for:

  • Stairways
  • Ramps
  • Escalators
  • Moving walkways
  • Required top and bottom 300mm from hazard
  • At landings if >3000mm depth of 600-800mm
  • At landings if < 3000mm depth of 300-400mm
  • If handrails provided both sides AND continuous NO TGSI
  • Overhead hazard
  • Depth of 600-800mm allows 300mm splay
  • Carriageways
  • Depth of 600-800mm

TGSI style and luminance contrast:

  • Integrated: 30%
  • Discrete: 45%;
  • Composite: 60%

Hazard TGSI

  • 300-400mm = 6no studs/600-800mm = 12no discrete studs
  • 25mm dia top 35mm max base/ 4-5 mm height
  • Placement = perpendicular to direction travel
  • Set back 300mm +-10mm edge hazard
  • If angled approach 600-800mm required
  • Directional TGSIs
  • Parallel with and along centreline path of travel
  • 300-400mm wide if in line path of travel
  • 600-800mm if across path of travel

Summary of Recommendations

  • Discrete and composite type TGSIs require maintenance if damaged missing or dirty.
  • For areas where directional TGSIs are considered important adequate lighting should also be provided.
  • Planning policy should provide building owners guidance on whether TGSIs can be provided on the footpath.
  • Bus stops to provide TGSIs to meet DDA Transport Standards.
  • Application of TGSIs requires careful planning to ensure safe wayfinding in the environment.
  • For upgrade works to pedestrian crossings hazard TGSIs should also be provided to adjoining (nonupgraded) areas to create a predictable environment.