Exploratory study to define new observation geometries for road lighting design

This paper focuses on the visibility of road users in urban environment. Firstly, a virtual reality experiment was carried out to determine where road users look on the road surface when travelling in city. The data collected were used to deduce observation angles for each type of road user. Measurements on an experimental site and simulations were carried out with these new observation angles. These were used to assess the impact of changing the observation geometry on the quality criteria of a lighting installation and on the visibility criterion. The results show that increasing the observation angle leads to a reduction in the average luminance but that, despite this, visibility is not affected. This led us to propose adaptations to the current recommendations: using a mobile observer for an observation angle greater than 1° and downgrading by one class when dimensioning a lighting installation in the city in the standard way, while taking into account the visual needs in an urban environment.