Overview
ISO 24508:2019 - Ergonomics - Accessible design - Guidelines for designing tactile symbols and characters - provides practical, evidence‑based guidance on designing tactile symbols and characters for people who rely on non‑visual or non‑auditory information. The standard covers convex (raised) tactile patterns touched by fingers and is applicable to products, facilities and equipment in housing, transportation, services and packaging. It specifies physical characteristics to maximize tactile legibility but does not prescribe semantic meaning (it excludes Braille and temporally/vibratory coded signals).
Key topics and technical requirements
- Scope and definitions: Defines tactile pattern, symbol, character, size, line width, raised height and tactile texture.
- Selection: Use simple geometric symbols and plain characters (avoid serif or decorative fonts); use outlined or filled raised patterns; use dotted/broken lines and textures for extended areas.
- Size requirements:
- Tactile symbols (except dots/lines): minimum 10 mm.
- Tactile characters: minimum 15 mm.
- Dots/bars sizing follows ISO 24503; when used together, dots < 1.5 mm and bars > 5 mm to avoid confusion.
- For older users not accustomed to tactile patterns, increase size by 1.5×.
- Line width: About one‑tenth of the symbol/character size; generally 0.5 mm–3.0 mm.
- Raised height: Recommended 0.3 mm–1.5 mm (exceptions allowed for special contexts; e.g., some warnings may use 0.25 mm).
- Cross‑section and safety: Prefer semicircular or trapezoidal cross‑sections; avoid sharp edges or rectangular cross‑sections to prevent discomfort or injury.
- Spacing and orientation: Provide sufficient spacing to prevent adjacent‑symbol interference; use upright (non‑italic) orientation.
- Other considerations: Ensure tactile signs are easy to find and touch, provide associated visual signs of the same meaning, and consider mounting height, angle and material.
Practical applications
ISO 24508 is used to design accessible tactile signage and markings for:
- ATMs, ticket machines and control panels
- Public transit signage and wayfinding
- Product packaging and service counters
- Built environment elements in housing and public buildings
It helps ensure raised symbols are legible by touch across age groups and sensory abilities, improving inclusive design and regulatory compliance.
Who should use it
- Accessibility and ergonomics specialists
- Industrial/product designers and UX/HCI professionals
- Architects and wayfinding consultants
- Manufacturers of tactile signage, controls and packaging
- Regulators and procurement teams specifying accessibility requirements
Related standards
Keywords: ISO 24508, tactile symbols, accessible design, tactile characters, tactile legibility, ergonomics, raised symbols, tactile signage.