Ecological impacts of traffic noise - A national spatial assessment for Sweden.

Sammanfattning: Increased utilization of terrestrial vehicles requires devotion of huge efforts to provide road infrastructure for increased accessibility. Meanwhile, there is no doubt that transportation infrastructure has major impacts on ecosystems, ecological processes and biodiversity at a landscape scale. These impacts result from habitat loss, fragmentation and degradation, spreading of invasive species, noise pollution, road mortality but also more unknown impacts such as altered isolation patterns. This study aims to picture probable impacts of noise in the current transportation infrastructure at a national scale in Sweden. The study involves mapping of potential conflict zones between roads and ecological networks by defining road-effect zones around roads based on traffic volume, surrounding vegetation type, land cover type and consequently noise level for each segment of the roads. Focal to this study are impacts of noise on areas of importance for nature conservation like key habitat areas, meadows, pastures and wetlands. A method called "Calculation of Road Traffic Noise" (CRTN) was selected for calculation of noise generated by traffic flows in Sweden .The analysis was performed by using data on roads from the National Road Database and SAMPERS, land cover data, data on biodiversity conservation, and national databases concerning nature values. The analysis was done with a spatial prediction model based on a Geographic Information System (GIS), using Sweden as a case study. According to the results, 813 ha of nature values are exposed to noise levels higher than 55 dB; same wise, 2190 ha of outlined areas with nature values are exposed to noise higher than 45 dB. The study provided baseline information and a broad prediction of main impacts on biodiversity at landscape and regional scales. Impact prediction of alternative planning scenarios will be facilitated using the GIS-based prediction models and assist decision making on allocation of future roads. Using such methods when discussing future localization of road infrastructure will be useful for integrated sustainability assessment and strategic environmental assessment. Thus, it provides possibilities for minimizing adverse impacts of infrastructure on biodiversity at an early planning stage.