GUIDE TO HI-VISIBILITY CLOTHING CLASSES

TO THE EN ISO 20471:2013+A1:2016 STANDARDS
(Including RIS-3279-TOM for UK Railways)

What is EN ISO 20471?

EN ISO 20471 is the international standard for high-visibility (hi-vis) clothing. It specifies the requirements for garments designed to visually signal the presence of the wearer in any daylight condition and under illumination by vehicle headlights in the dark.

The standard defines minimum areas and placement of fluorescent background material and retroreflective material. Based on the surface area of these materials, garments are classified into three visibility classes (Class 1, Class 2, and Class 3), with Class 3 being the highest level of visibility.

Classes of Hi-Vis Clothing

Class 1 (Lowest Visibility)

Provides the minimum level of conspicuity.
Suitable for low-risk environments where traffic is slow-moving (<30mph).

Class 2 (Intermediate Visibility)

Offers a higher level of visibility for medium-risk environments.
Suitable for roadworks, site traffic, or working near moving equipment.

Class 3 (Highest Visibility)

Maximum conspicuity in high-risk environments.
Must have sleeves and full torso coverage to achieve Class 3 status.
Mandatory where workers are exposed to high-speed traffic (>50mph) or poor visibility conditions.

RIS-3279-TOM (Rail Industry Standard)

In addition to EN ISO 20471, anyone working on or near the UK railways must comply with RIS-3279-TOM, a requirement set by Network Rail.

Key points:

Specifies that hi-vis garments must be orange (not yellow) for enhanced distinction against railway backgrounds.
Garments must meet at least Class 2 of EN ISO 20471.
Retroreflective tape must meet the same standards and be positioned to ensure 360° visibility.

This ensures workers are immediately visible to train drivers, even at long distances and in low-light conditions.

Class / Standard	Fluorescent Background (m²)	Retroreflective Material (m²)	Minimum Requirement / Typical Use
Class 1	0.14 m²	0.10 m²	Low risk, slow traffic (<30mph)
Class 2	0.50 m²	0.13 m²	Roadworks, general construction, site traffic
Class 3	0.80 m²	0.20 m²	High-speed roads (>50mph), poor visibility conditions
RIS-3279-TOM (Railway)	As Class 2+	As Class 2+	UK railways — must be orange and minimum Class 2

Selecting the Right Class for Your Work

When selecting hi-vis clothing, carry out a risk assessment by considering:

1 — Work Environment

Are you working near fast-moving traffic, heavy machinery, or rail lines?
Are conditions often low-light, foggy, or poor weather?

2 — Task Type

Will you remain in one area or move across multiple risk zones?
Do you need freedom of movement that may rule out bulkier garments?

3 — Legal Requirements

Road workers must wear at least Class 2 garments.
Railway workers must comply with RIS-3279-TOM (Class 2+ orange).
High-risk sites often require Class 3 for all operatives.

Practical Guidance

Layering: Combining garments can raise the overall class (e.g., a Class 2 vest with Class 2 trousers may achieve Class 3).
Fit and Coverage: Hi-vis material must not be obscured by bags, harnesses, or dirt. Always ensure reflective bands are unbroken and visible.
Garment Care: Washing can reduce reflectivity over time. Follow care instructions and replace garments when they no longer meet brightness and retroreflection standards.