The GO/RT 3279 standard ensures garments meet at least class 2 of EN ISO 20471 for the minimum area of high visibility materials used within a garment.
The background material must be fluorescent orange with chromaticity and luminance. The change in chromaticity after light exposure and colourfastness shall conform to the requirements of EN ISO 20471:2013 High Visibility Clothing for Professional Use.
The photometric and physical performance requirements for the retro reflective material shall conform to the requirements stipulated in EN ISO 20471:2013, class 2 - Intermediate Protection Level: Bands of retro reflective material shall not be less than 50mm wide. Minimum background material 0.50m2. Minimum retro reflective material 0.13m2.
Except in the clothing worn by a Rail Incident Officer or First Aider, the background material shall not be obscured by the addition of any other features, unless provision has been allowed for in the specification such that the minimum areas of background and retro reflective material have been preserved.