GIS-based Visualisation of Traffic Noise

Abstract

Among the environmental problems emerged in the majority of modern cities, noise pollution along with air pollution is considered to be the most important ones. Traffic noise is a priority issue in the EU. According to a Commission Green Paper. Environmental noise caused by traffic, industry and recreation is identified as one of the main local environmental problems in Europe. Various methods simulating traffic noise have been developed (NMBP, NAC. CRTN etc.). These methods focus on the impacts of numerous factors on the final noise levels such as the distance from the noise source, the nature of the ground surface, the intervening obstructions, the purpose-built barriers, as well as other factors affecting the propagation of sound waves, such as reflection from nearby surfaces, absorption, attenuation, diffraction etc. Computer models implementing noise methods also support a map-based representation of the final noise levels on the area under study. However, there is enough space for improvements, not only with respect to the integration between the map elements representing the above factors and the software implementing the noise method, but also to the final visualisation of traffic noise levels. Hardware evolution, reflected to processing capacity, provide the capability of storing, processing and manipulating large datasets of spatial information as well as managing and visualising large image files. In addition, contemporary GIS tools support analysis and design of complex systems, as well as simulation of any critical parameter governing such systems. In this respect ArcGIS tools have been employed to represent all the objects that generate noise and affect its propagation at a specific area of the city of Thessaloniki. The site comprises a two branch (3-lane each) segment of the ring road of the city, a residential area located right next to the highway and a series of noise barriers placed across the edge of the road in order to reduce the final noise levels reaching the buildings. Traffic noise entities, digitised according to GIS principles along with the topography of the studied area, constitute various vector and raster thematic areas. Furthermore, by using extensions supporting spatial analysis it has been possible to perform a grid-cell analysis in the area under consideration. By this, any of the above described factors that affect the propagation of the sound waves v/as plotted in a raster layer, and in turn all the layers were combined so that every discrete unit contains and represents the total noise.