Knowing the ability of a coating to reflect light (pavement photometry) allows the design of optimised road lighting facilities. Currently, these characteristics are little known and poorly taken into account, including in European standards. The objective of the SURFACE project is to remedy these shortcomings, both for measurement methodologies, characterisation in urban environments and reduction of light pollution.
Currently, in Europe, around 40% of the 5.5 million kilometres of roads are lit. European road lighting standards (EN 13201: 2016 series 2-5) specify values for luminance and uniformity of the illuminated road surface. The aim is to meet the performance of the standard classes in terms of safety, visual appearance and power consumption. The reduced luminance factor r (ratio between the luminance of the pavement surface and the illumination for given directions of illumination and observation) characterises the photometry of the road. Usually, the design of these lighting systems (e.g. the definition of layout, light intensity distribution of the light fittings and the luminous flux installed per kilometre, or the power density indicator) takes into account the r reference data of the road surface.
In EN 13201, a series of road lighting standards, standard r tables are provided and in general the actual characterisation of the road is missing. Naturally, the lighting designer adopts the standard tables as the de facto standard values published in the ICE documents. These tables are based on measurements taken on samples collected more than 40 years ago, with no traceability or uncertainty assessment.
Recent studies have shown that the use of these reference data leads to large errors (on average more than 30%, but up to 50% in worst cases) in expected road luminance. Moreover, the photometric properties of road materials have evolved over time, as have road lighting systems (LED sources, adaptive systems and intelligent lighting systems). Such an evolving situation requires the definition of new r values and an upgrade of the reference directions for its measurement. To ensure that the EU's goal of energy saving and road safety is met, it is time to improve the reference data and reference geometries through a large metrological research study on fundamental concepts and measurement campaigns.
The objective of this project is to remedy the current shortcomings of European standards with regard to:
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Definition and characterisation of road surface photometry: Development of optimised measurement geometries for the characterisation of photometric quantities of road surface materials in view of the EN 13201 "Road lighting" standard and its future revisions.
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Road photometry measurement methods:
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Drafting of technical and metrological specifications for instruments used to measure luminance and reduced luminance factors of road surfaces in laboratories or on-site, including calibration methods, traceability and measurement uncertainty.
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Integration of spectral characteristics and light pollution: Drafting of pre-normative guidelines for measurement methods and procedures, with a view to the future evolution of European standards to include aspects such as mesopic visual conditions (CIE191: 2010), annoying light reduction and reduction in light pollution from road lighting facilities.
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Traceable reference data for photometric tables useful in the road lighting facility design process:
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Drafting of pre-normative guidelines for the photometric characterisation of road surfaces and pavements, including factors such as ageing of road surfaces, wet conditions, spectral properties, diffusion of adaptive lighting systems (intelligent lighting), distribution of luminous intensity of light fittings and the effects of measurement uncertainty on tolerance calculations.
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Contribution to the standard development work of the CEN TC169 / WG12 and ICE TC4-50 technical committees through the provision of data, methods, guidelines and recommendations. In particular to provide traceable data relating to new geometries and materials to be included in the updated pavement photometric tables in the international ICE database.
The common SURFACE research project will carry out the metrological research and set up the associated infrastructure, i.e. measurement methodologies, reference data, new geometries and new reference materials for the calibration of instruments. The aim is to achieve a more efficient, more sustainable and safer design of road lighting by the new edition or revision of the EN standards that will be used by night road users in the EU.
In particular, this project will select a new set of geometries capable of representing the most useful and significant directions of lighting and vision for solid-state lighting (SSL), urban areas and various users. It will take into account glare assessment and the new vision models.
In terms of metrology, it will provide guidelines for measuring instruments and procedures, for calibration and evaluation of uncertainty, methods for evaluating the influence of ageing, spectral properties and wet conditions. For this, an inter-comparison of measurements on reference materials will be carried out and open source CC uncertainty calculation software will be developed.
Surface will provide the standardisation body and ICE with new reference data for the characterisation of road photometry, with declaration of uncertainty, for the current reference geometries of standard EN 13201 and for future geometries.
Upon completion of the project, the EU market will benefit from a certified reference material for the calibration of road surface measuring instruments and a prototype portable measuring instrument for the new geometries.
The project notably provides for the production of pre-normative guides:
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For the photometric characterisation of road surfaces and pavements, including measurement methods and procedures, ageing of road surfaces, wet conditions and spectral properties;
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For applications in the field of road lighting, including the effects of measurement uncertainty in the calculation of tolerances, the contribution to disturbing lights and to light pollution of road lighting facilities, taking into account road reflectance, mesopic visual conditions and adaptive lighting systems (intelligent lighting).
Cerema is participating in the entire project and is leading workpackage 2 «Applications».
Its contributions concern in particular:
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The collection and analysis of data characteristic of European pavements aimed at proposing new standard tables;
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Integration of the spectral characteristics of lighting;
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The development of new characterisations of road surface photometry, better suited to the urban environment in particular;
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Improvement of the systems for characterising the photometry of Cerema coatings (the goniophotometer for laboratory measurements and Coluroute2 for on-site measurements) using the new geometries;
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Measurements and analysis in the context of cross-tests.
The project is led by INRIM, Italian metrology institute and has as partners AALTO (Finland), LNE (France), METROSERT (Estonia), RISE (Sweden), METAS (Switzerland), CEREMA (France) and the companies OPTIS (France) and ZEHTNER (Switzerland). For Cerema, the project is led by Valérie Muzet, from the ENDSUM research team, and also involves the ITS research team from Clermont Ferrand. It is intended to supply the Public Lighting group at Cerema.
The EMPIR SURFACE project (16NRM02), lasting 3 years, started in July 2017. This is a EURAMET-type project which, as such, mainly brings together metrology institutes.
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