National foreword

This Published Document is the UK implementation of CEN/TS 18350:2026.

The UK participation in its preparation was entrusted to Technical Committee B/509/3, Construction of road traffic signs.

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

This publication is not to be regarded as a British Standard.

Compliance with a Published Document cannot confer immunity from legal obligations.

This Published Document was published under the authority of the Standards Policy and Strategy Committee on 31 October 2026.

This Technical Specification (CEN/TS) was approved by CEN on 31 August 2026 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and United Kingdom.

European foreword

This document (CEN/TS 18350:2026) has been prepared by Technical Committee CEN/TC 226 “Road equipment”, the secretariat of which is held by AFNOR.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

Any feedback and questions on this document should be directed to the users’ national standards body. A complete listing of these bodies can be found on the CEN website.

According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United Kingdom.

Introduction

This document provides performance requirements and test methods for retroreflective sheetings independent of the manufacturing technology. It introduces a complex test method, that considered different sign positions and mounting directions of the processed material.

Retroreflective sheetings are usually manufactured based on glass bead or microprismatic technology.

Further, this document introduces performance-based classes of retroreflection (each divided into two subclasses). These were derived in correlation with the luminance of traffic signs from the driver's perspective to enable the subsequent use of reflective sheeting as a sign face material for traffic signs. The classes are developed with the concept of constant luminance to the driver during the approach to the sign. The background for the luminance based retroreflective classes is described in an informative Annex C.

The visual performance of retroreflective sheetings is dependent on their luminance and chromaticity. Retroreflection is the relevant characteristic for the legibility and visibility of signs during nighttime driving, while luminance factor and chromaticity are relevant characteristics for the legibility of signs during the daytime (and for illuminated signs at night).

Retroreflection is measured by the specific coefficient of retroreflection R_A, which is in principle a function of four angles needed to describe the geometry of retroreflection.

To deal with this complex geometry, this Technical Specification introduces the R_A,C(α,β) value, which is a calculated value of the specific coefficient of retroreflection R_A for a combination of the observation angle α and the entrance angle β. The R_A,C(α,β) value is calculated from various R_A measurements in which two additional angles have been varied.

Test methods to measure the specific coefficient of retroreflection are provided in Annex A and for luminance factor and chromaticity in Annex B. Both annexes are of a complex technical nature, as they deal with retroreflective sheetings of various technologies and because the fluorescence of fluorescent retroreflective sheetings has been considered. These normative annexes are primarily intended to be studied by experts working at test laboratories.

1 Scope

This document describes the performance requirements and test methods for retroreflective sheetings. This document only applies to products that do not fall under the scope of EN 12899 (all parts) and EAD 12001‑01‑0106, Microprismatic retro-reflective sheetings, with the intended use as retroreflective sheeting for permanent traffic signs or retroreflectors for delineators.

2 Normative references

3 Terms and definitions

4 Characteristics

4.1 Retroreflection

4.2 Daylight chromaticity coordinates and luminance factor

4.3 Durability - Resistance to weathering

5 Testing, assessment and sampling methods

5.1 Test conditions

5.2 Test specimen

5.3 Testing for mounting axis symmetries

5.4 Derivation of R_A,C(α,β) values

5.5 Colorimetric testing

5.6 Accelerated weathering