Träds inverkan på belysningseffekt på gång- och cykelvägar

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Annika Jägerbrand

Trees and vegetation in the street environment are important components of urban areas and they increase the environmental quality in cities. The purpose of this study was to examine the influence of trees on shade effects (illuminance and spectral distribution) in pedestrian and bicycle paths by quantifying the reduction of streetlight caused by tree intrusion in order to give recommendations for the management and maintenance of trees in the street environment. Measurements of the shading were tree intrusion and tree area as well as changes in R/FR. R/FR is a measurement on how shade from vegetation affects the spectral distribution. The results show that any type of intruding vegetation into the sidewalk area has a potential blocking effect on the illuminance and that the effect increased the more the trees are infringing. Tree shadow caused the illuminance to drop between 27-77%. Current guidelines for free height above pedestrian zones, bicycle roads and driving lanes are consequently not high enough to prevent shade effects by trees. The free height of vegetation and trees should be as high as the lighting pole in order to avoid light reductions due to tree intrusion.

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