Design you can feel.
Access you deserve.
Stainless steel is the default material for tactile indicators in transport and public infrastructure because it combines two things: it lasts for decades without maintenance, and it can be manufactured to the tight dimensional tolerances that accessibility standards demand. This guide covers both aspects for specifiers.
AISI 304 (18% chromium, 8% nickel) resists corrosion in normal indoor and inland outdoor conditions and is the standard grade for MetalX stainless steel tactile studs, strips and tiles. AISI 316 adds 2–3% molybdenum, which prevents the chloride pitting that attacks 304 in coastal air, marine terminals, pool surrounds and on roads treated with de-icing salt. Specify 316 within about 5 km of the sea or wherever chlorides are present. Both grades are supplied with mill test certificates.
MetalX machines studs and bars from solid bar stock rather than pressing thin shells. A solid stud cannot dent under a trolley wheel, cannot be crushed by a floor scrubber and keeps its surface pattern for the life of the building. Tiles are pressed from 1.8 mm sheet with the option of welded solid studs for the heaviest duty.
Concentric rings and diamond knurling are machined into the top and wear very slowly. Carborundum inserts (silicon carbide grit in resin) give the highest wet slip resistance and can be renewed if ever worn. PVD colour coatings are titanium-nitride layers harder than the steel itself; they do not chip like paint.
Stem-fixed studs set in epoxy or polyester anchor adhesive are the most durable option for exteriors and platform edges. Poly sleeves isolate the stem and take up hole tolerance. 3M self-adhesive fixing is permanent on smooth, dense interior floors. Screw-fix studs suit carpet and timber. Whatever the fixing, the failure mode of a stainless steel indicator is almost always the substrate or the installation, not the stud.
Accessibility standards define the shape, size and spacing of warning and directional indicators, the depth and setback of warning fields, and the visual contrast with the floor. They do not specify material or fixing method.
| Standard | Warning (attention) indicators | Directional (guiding) indicators | Contrast |
|---|---|---|---|
| ISO 23599:2019 | Truncated domes / cones; top 12–25 mm, height 4–5 mm, spacing 42–61 mm | Bars 17–30 mm top width, height 4–5 mm, spacing 57–78 mm | Required; tested luminance contrast |
| AS/NZS 1428.4.1:2009 | Truncated cones 35 mm base / 25 mm top, 4–5 mm high, 50 mm centres | Bars 35 mm base / 25 mm top, 4–5 mm high, 75 mm centres | 30% integrated, 45% discrete, 60% composite |
| ADA 2010 §705 (USA) | Truncated domes 23–36 mm base, top 50–65% of base, 5.1 mm high, 41–61 mm centres | Not mandated | Visual contrast light-on-dark or dark-on-light |
| BS 8300-1:2018 / DfT (UK) | Blister and corduroy surfaces per DfT guidance | Guidance path surface (flat-topped bars) | Required, with colour conventions (red at controlled crossings) |
| India Harmonised Guidelines 2021 / IRC:103 | Warning blocks (domes) at hazards and level changes | Guiding blocks (bars) from entrances to facilities | Required; yellow commonly used |
The MetalX standard stud (Ø35 mm, 4.5 mm, 50 mm centres) and bar (35 mm wide, 4.5 mm high, 75 mm centres) match AS/NZS 1428.4.1 and fall within ISO 23599 ranges. For ADA projects a truncated-dome profile with a smaller top is supplied. See the full standards comparison.
Most standards require a warning field 600 mm deep (ADA: 610 mm) across the full width of the hazard, set back about 300 mm from a stair nosing or platform edge (AS/NZS 1428.4.1: 300 ± 10 mm). Confirm the governing standard on each project.
Bright stainless steel on grey granite may not achieve the luminance contrast required. Solutions: PVD colour coating (black, bronze, gold), coloured polyurethane inserts, black carborundum inserts, or a contrasting band of paving around the field. MetalX can advise on the option that satisfies your standard.
SS 316. Its molybdenum content resists chloride pitting from sea air and de-icing salt. SS 304 is adequate for inland and indoor sites.
The standard Ø35 mm, 4.5 mm high stud at 50 mm centres falls within the ISO 23599 attention-pattern ranges and matches AS/NZS 1428.4.1. Confirm the governing standard on your project and we will supply the matching profile.
Typically 600 mm in the direction of travel (610 mm under ADA), across the full width of the hazard, set back about 300 mm from a stair nosing or platform edge.
Use PVD colour coating, coloured polyurethane inserts, black carborundum inserts or a contrasting paving band around the tactile field.
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27 March 2026 · 5 min readPlatform-edge fields, guiding paths to gates and lifts, SS 316 in coastal cities, drawings and certificates: what a contractor should expect in a metro tactile specification.
20 May 2026 · 6 min readSend us your drawings, quantities and delivery location. We reply with a quotation, technical datasheet and lead time, usually within one working day.