Tactile Ground Surface Indicators (TGSI) Guide | Line
TGSIs provide critical navigation cues for people with vision impairment. Understanding AS/NZS 1428.4.
Tactile Ground Surface Indicators (TGSI) Guide
A new shopping centre in Craigieburn installed tactile indicators throughout their carpark and entrances. Three months later, they received a complaint: the warning indicators at a hazard were installed as directional bars instead of dots. For someone using a white cane, bars mean 'follow this direction'—not 'danger ahead.'
Tactile Ground Surface Indicators (TGSIs) are textured ground surfaces that provide navigation information to people with vision impairment. Getting them wrong doesn't just breach the Disability Discrimination Act—it creates genuine danger for vulnerable users. — see our pedestrian safety marking services
What Are TGSIs?
TGSIs are raised textured surfaces detectable underfoot and by long cane. They communicate two types of information: hazard warnings and directional guidance. People with vision impairment learn to interpret these textures through orientation and mobility training. Learn more about our accessible parking line marking
The Two Types:
Warning TGSIs (Dots):
Pattern of raised truncated domes (dots) arranged in a grid. These indicate hazards ahead—stop and assess before proceeding. Used at kerb ramps, stair landings, platform edges, and other hazard points.
Directional TGSIs (Bars):
Pattern of raised parallel bars oriented in the direction of travel. These guide users along a path—follow the bars to continue safely. Used to guide across open spaces or indicate the direction of an accessible route.
Applicable Standards
TGSI requirements are specified in AS/NZS 1428.4.1:2009 Design for access and mobility - Means to assist the orientation of people with vision impairment - Tactile ground surface indicators. Learn more about our accessible parking requirements
This standard is referenced by the National Construction Code and the Disability (Access to Premises - Buildings) Standards 2010, making compliance mandatory for new buildings and major renovations.
Where TGSIs Are Required
Warning TGSIs Required At:
- Pedestrian crossings and kerb ramps
- Top and bottom of stairs and ramps
- Escalator approaches
- Railway platform edges
- Overhead obstructions below 2000mm
- Vehicle crossings on pedestrian paths
Directional TGSIs Used For:
- Guiding across large open spaces (plazas, concourses)
- Indicating accessible path direction after warning TGSIs
- Connecting between building entrances and transport stops
Dimensional Requirements
AS/NZS 1428.4.1 specifies precise dimensions for TGSI elements.
Warning TGSI Dots:
- Base diameter: 25-35mm
- Top diameter: 15-25mm
- Height: 4-5mm
- Centre-to-centre spacing: 50-55mm
Directional TGSI Bars:
- Width at base: 17-30mm
- Width at top: 10-20mm
- Height: 4-5mm
- Centre-to-centre spacing: 45-55mm
Colour and Luminance Contrast
TGSIs must have adequate luminance contrast with the surrounding surface so people with low vision can detect them visually.
Requirements:
- Minimum 30% luminance contrast with surrounding surface
- Yellow and off-white are most common colours
- Black may be used on light-coloured surfaces
- Colour must be integrated, not surface-applied paint
Yellow is preferred in most situations as it provides good contrast against grey concrete and dark asphalt while being widely recognised.
Installation Methods
Discrete Units:
Individual tactile studs installed into drilled holes. Good for retrofitting existing surfaces. Requires precise drilling and adhesive application. Best for concrete and stone surfaces.
Integrated Tiles:
Pre-formed tiles with TGSI pattern incorporated. Easier installation, consistent spacing. Available in various materials including rubber, polyurethane, and ceramic.
Surface-Applied Systems:
Flexible polyurethane tiles adhered to existing surfaces. Quick installation, suitable for retrofits. May have shorter lifespan than embedded systems in high-traffic areas.
Common Installation Errors
We regularly see TGSI installations that fail compliance or create hazards.
- Wrong type used (bars where dots required, or vice versa)
- Incorrect orientation of directional bars
- Insufficient depth (300mm minimum for warning)
- Poor luminance contrast with surroundings
- Installed too far from hazard edge
- Missing TGSIs at required locations
Request a TGSI compliance assessment or installation quote
Frequently Asked Questions
Are TGSIs required in carparks?
Yes, at specific locations: pedestrian crossings, kerb ramps, stair approaches, and along accessible paths of travel. They're critical where vehicle and pedestrian traffic interact.
Can we paint TGSIs to refresh the colour?
No. Painting fills the gaps between elements and reduces tactile detectability. If TGSIs have faded, they should be replaced with new units that have integrated colour.
What's the difference between Australian and overseas TGSIs?
Different countries use different patterns and meanings. Products must comply with AS/NZS 1428.4.1 specifically. Japanese or US patterns are not compliant in Australia and may communicate incorrect information. For professional assistance, contact our carpark line marking Melbourne team
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Frequently Asked Questions
What is the difference between warning and directional TGSIs?
Warning TGSIs are a grid of raised truncated domes, or dots, that mean stop and check for a hazard ahead, such as a kerb ramp, stair or platform edge. Directional TGSIs are raised parallel bars laid in the direction of travel that guide people along a safe route. Using the wrong TGSI type creates a genuine danger.
How deep should a warning TGSI area be?
A warning TGSI area must be at least 300 mm deep in the direction of travel under AS/NZS 1428.4.1:2009, and it must be placed the correct distance from the hazard edge. A warning TGSI strip that is too shallow, or installed too far from the edge, can be missed by a person using a long cane.
What colour should TGSIs be?
TGSIs must have at least 30% luminance contrast with the surrounding surface. Yellow is the most common TGSI colour because it stands out against grey concrete and dark asphalt, off-white is also used, and black can suit light-coloured surfaces. The colour must be integrated into the TGSI, not surface-applied paint.
What size are TGSI dots and bars?
Under AS/NZS 1428.4.1:2009, warning TGSI dots have a base diameter of 25–35 mm, a top diameter of 15–25 mm and a height of 4–5 mm, at 50–55 mm centres. Directional TGSI bars are 17–30 mm wide at the base, 10–20 mm wide at the top and 4–5 mm high, at 45–55 mm centres.
Are TGSIs mandatory in Australia?
TGSIs are mandatory for new buildings and major renovations because AS/NZS 1428.4.1:2009 is referenced by the National Construction Code and the Disability (Access to Premises – Buildings) Standards 2010. Getting TGSIs wrong can also breach the Disability Discrimination Act and create real danger for people with vision impairment.
How are TGSIs installed on existing concrete?
On existing concrete, TGSIs are usually installed as discrete studs set into drilled holes with adhesive, or as surface-applied flexible polyurethane tiles. Discrete TGSI studs suit concrete and stone retrofits, while surface-applied tiles are quicker to install but may not last as long in high-traffic areas.
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Written by
Nizi BhandaryLine Marking Specialist, Line Marking Australia
Nizi Bhandary is a line marking specialist with Line Marking Australia, working hands-on across car park, warehouse, road and sports-court projects nationwide. Nizi focuses on AS/NZS 2890 and AS 1742 compliant work and writes these guides to help facility managers, builders and councils get compliant, long-lasting line marking — without the guesswork.
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