16NRM02 SURFACE: Pavement surface characterisation for smart and efficient road lighting

• Forschungsstelle: METAS
• Projektnummer: F-5116.30089

Schlüsselwörter (Englisch)

Road Lighting, Road surface photometry, Road safety, Energy Saving, Smart Lighting, Smart cities, Innovative pavements

Kurzbeschreibung (Englisch)

This project will provide validated, optimised and reliable geometrical conditions for the measurement of road surface reflectance spatial distribution characteristics (the so called luminance coefficient q or reduced luminance coefficient r) and new data representative of current road pavements. The knowledge of q is an unavoidable requirement for designing road lighting installations for motorised traffic and is needed to be able to assure that road luminance is adequate for visual conditions and traffic safety. However, the current reference tables of r do not provide values for all directions acknowledged in the relevant standards. For example data is missing or is often based on measurements performed more than 40 years ago.
Therefore, new validated data is needed for pavements, LED and smart lighting systems in order to support the enhancement of performance for visual optimisation, energy efficiency and safety as set out in current Road Lighting Standards.

Current EU standards on road lighting (i.e. EN 13201 series 2-5) seek to establish road luminance values able to satisfy quantitative and qualitative performances in terms of safety, visual appearance and energy consumption. Thus the weighting and spacing of a road lighting system (i.e. flux installed per kilometre) is calculated accordingly and ensures compliance with the suggested luminance values of the assigned road class. However such calculations are currently based on measurements made on concrete samples more than 40 years ago and recent studies have shown that the available reference data lead to large errors (on average over 30 % but up to 50 %). Moreover, the photometric properties of road materials have evolved over time but the reference data has not.

This is a joint research project carried out in the framework of the European Metrology Programme for Innovation and Research (EMPIR) (see:http://www.euramet.org/research-innovation/empir/). The EMPIR initiative is co-funded by the European Unions's Horizon 2020 research and innovation programme and the participating states. METAS is one of the project partners in the Project.

Projektziele (Englisch)

The goal of this project is to address the current deficiencies in European Standards regarding (i) the definition and characterisation of the road surface photometry, (ii) traceable measurement and characterisation methods for road surface characteristics and (iii) traceable reference data for photometric tables. The results will be used by CEN TC169/WG12 in the next revision of EN 13201 series, and by CIE TC4-50 in current CIE publications under revision.

The specific objectives are:

1. To develop optimised measurement geometries for the characterisation of photometric quantities for road surface materials to support EN 13201 ‘Road Lighting’ and its future revisions.
2. To produce technical and metrological specifications for instruments used to measure luminance and reduced luminance coefficients of road surfaces in laboratories or on-site, including methodologies for calibration, establishing traceability and evaluating the measurement uncertainty.
3. To develop pre-normative guidelines for measurement methods and procedures, for the future evolution of European standards to include aspects such as mesopic visual conditions (CIE191:2010), reduced obtrusive light and reduced light pollution of road lighting installations.
4. To develop pre-normative guidelines for photometric characterisation of road and pavement surfaces, including factors such as aging of road surfaces, wet conditions, spectral properties, diffusion of adaptive lighting systems (smart lighting), luminaire luminous intensity distribution and effects of measurement uncertainty in tolerance calculations.
5. To contribute to the standards development works of the technical committees CEN TC169/WG12 and CIE TC4-50 through the provision of data, methods, guidelines and recommendations. In particular to provide traceable data related to new geometries and materials for inclusion in updated photometric tables of pavements in the international CIE database. To ensure that the outputs of the project are aligned with their needs, results will be communicated quickly to those developing the standards and to those who will use them (e.g. lighting engineers, road designers), and in a form that can be incorporated into the standards at the earliest opportunity.

Abstract (Englisch)

The aim of the EMPIR pre-normative project "SURFACE" is to provide the metrological foun-dations for the photometric characterisation of road surfaces. The projects includes the realiza-tion of reference materials to be used for the calibration of measurement devices. In addition, an extensive study of the measurement uncertainty was made, an inter-laboratory comparison was performed and different guidance documents were written.

Umsetzung und Anwendungen (Englisch)

General level:
Presently in Europe about 40 % of the 5.5 million kilometres of roads have lighting. Current EU standards on road lighting (i.e. EN 13201 series) seek to establish road luminance values able to satisfy quantitative and qualitative performances in terms of safety, visual appearance, energy consumption, and light pollution. The goal of reducing energy consumption can only be reached by different measures, including optimization of the illumination systems, smart lighting systems (using sensors), onsite measurements and training of lighting design engineers. The optics laboratory of METAS is active in all four activities. The results of this project contributes to the optimization of illumination system directly: International application standard specify minimum light levels. The installed illumination levels can be lowered to the minimum required illumination levels only through a proper measurement uncertainty analysis whereby the reflectance of the road surface plays a dominant role.  

Direct utilization of the results:
The project helped identify problems regarding the European road lighting standard EN 13201. New measurement angles should be defined, especially for urban zones, for a better evaluation of glare and light pollution. The extended luminance coefficient table cannot currently be measured neither in laboratory nor in the field, and such measurements are extremely difficult to achieve with tolerable uncertainty. The project also provided evidences that the reference road surfaces defined by CIE needs to be updated. This is particularly important when designing road lighting installations. Using a reference r-table that is not representative of the road surface was shown to produce large deviations from an optimized case. This can lead to energy overconsumption or non-conformity to the norms. The results from the SURFACE project will also directly feed CIE TC 4-50 Road Surface Characterization for  Lighting Applications revising the fundamental guidance document CIE 066-1984 Road surfaces and lighting (joint technical report CIE/PIARC). The current chair of the committee was part of the SURFACE project, which will ensure a smooth overtake of the different results.

Benefits for METAS:
The benefits from the project for METAS are numerous. First, in term of collaboration, the project strengthened the contact with the Swiss partner, Proceq - Screening Eagle Technologies. Proceq is now reaching out to us for a number of other services. It also supported a strong collaboration with different groups, in particular INRIM, CEREMA, RISE and LNE, which are valuable partners for further advancement of the subject. In terms of technical benefit within METAS, the project supported the characterization of two measurement setups (LaFOR and MoFOR) used in the Optics Laboratory, some of which are regularly used for services (LaFOR). The project paved the way for a rigorous measurement uncertainty analysis of those setups, which has a big impact in regards to QS. The simulation tool LUMCORUN developed within the project will help characterize all the setups used for surface photometry characterization. In particular, in can be used for the setup LTL-200, which is the portable instrument used for measurement in tunnels. This setup is an important part of the laboratory service in tunnels, and establishing its full uncertainty budget is an important step towards a service of even better quality. The application of the methods developed in this project to our measuring device will probably take place within the framework of an internal "Kleinprojekt".