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Laboratoire Angevin de Recherche en Ingénierie des Systèmes

Separated by coma

Defense of Ms. Laure LEBOUC thesis2:00 | Amphi A | POLYTECH ANGERS | 62, avenue Notre-Dame du Lac 49000 ANGERS

Subject : Simulation, evaluation and optimization of night-time legibility of urban developments: taking into account the light-reflecting properties of pavements for lighting adapted to the various users of public space.

Director of thesis: M. Paul RICHARD


Today, adapting to climate change is an increasingly important issue, and much thought is being given to integrating this imperative into city planning and development. In this context, reducing the energy costs associated with public lighting is a preferred means of action for which three levers can be considered. The first concerns lighting sources, by replacing energy-guzzling sources with more energy-efficient LED technologies. The second involves taking better account of the optical properties of road surfaces when designing lighting installations. The third lever concerns users and their specific observation requirements, depending on their mode of travel.

Performance requirements for road lighting are defined by considering a geometry that corresponds to a motorist travelling on an interurban road at a speed of between 70 and 90 km/h. However, most street lighting is located in urban areas, where the average speed is between 30 and 50 km/h, and where users include not only motorists, but also cyclists and pedestrians. 

This research project proposes a paradigm shift in the way night-time urban design is conceived, by placing the light-reflecting properties of pavements at the heart of the design of urban lighting installations, and by giving greater consideration to the different uses of public space, taking into account the differences in perception between users.

For this purpose, an urban lighting calculation engine has been developed, allowing light sources, road surfaces and viewing angles to be varied. From this, the performance criteria defined in the standards can be determined. To go a step further, a visibility calculation has been integrated into the software, following the well-known Adrian (VL) visibility level model for road lighting applications, which we have adapted to take account of lighting reflections on the road surface.

In addition, we carried out an experiment with virtual reality subjects coupled with eye-tracking to find out where users look on the ground as they travel. This enabled us to study the influence of the mode of travel (pedestrian, cyclist, motorist) on the average angle of observation in a night-time urban environment. Lighting calculations and on-site measurements were then carried out using the average observation angles obtained by type of user for different lighting situations with different road surfaces. This enabled us to study the influence of the road surface and its photometric properties. On the other hand, it allowed us to analyze whether these differences in observation angles mean that current lighting dimensioning standards need to be revised to take account of all road and urban space users.

Key words
Street lighting, urban planning, optical properties of pavements, visibility, virtual reality.