CONAT20103029 OPTIMIZATION METHODS OF URBAN RAIL TRANSPORTATION AND POPULATION EXPOSURE CALCULATION Janos Timar, Mariana Dominica Stanciu, Corneliu Cofaru, Daniela Florea, Anghel Chiru, Dinu Covaciu Transilvania University of Brasov, Department of High Tech Product for Automotive, Romania KEYWORDS –population exposure, noise map, rail noise optimisation, noise barrier, noise modelling ABSTRACT – Noise is a major source of dissatisfaction in residential areas. There are many noise sources in the urban areas, but only some of them can be taken into consideration for noise mapping and noise reduction action planning. These are: road traffic, railway traffic, airports and industry. The research paper intends to make the optimized noise map of the rail transport of Tg. Mureş city. The local authorities mentioned that they would like to reduce in the future the rail noise. Therefore it was made some investigation and resulted that one optimization could be that along the rail line where the buildings are close to one another, noise barriers could be mounted, reducing the rail noise in this way with 5 – 10 dB (A). Another optimization is welding the rail joints and reducing the speed limitation to 50 km/h along the urban area resulting a 2 dB (A) reduction. INTRODUCTION Noise is a major source of dissatisfaction in residential areas. There are many noise sources in the urban areas, but only some of them can be taken into consideration for noise mapping and noise reduction action planning. These are: road traffic, railway traffic, airports and industry – see references [3],[5],[1]. In order to know the effect of these noise sources on the population and buildings, we have to know as much as possible about the sources and propagation. The analysis can be done using specialized software. The result is a noise map – a map representing the noise levels as surfaces or contour lines. The input data for the simulation software are a base map and specific properties of the sources (road segments, railway segments, industrial sources and others). POPULATION EXPOSURE CALCULATION Population calculation could be done easily if for each building along the railway is known the number of inhabitants (stored as metadata). From the noise map is possible to identify the exposure of each façade of the building to each noise level (Figure 2). The grid cells are colored according to the equivalent noise level (intervals of 5 dB). The exact noise value is stored as Z coordinate of the cell; adding this value as metadata is not a good idea because the very high number of cells will make the execution of any other command very slow. The first step is to find all the intersections between the building contour lines and the squares representing the grid cells in the noise map. Only the x, y coordinates are used to calculate the intersections, because z is the noise value. For each intersection found the value of the noise associated to the respective grid cell is added to a list – the black list in Figure 1. This list is added to the building object in the drawing as metadata. Figure 1. Metadata associated to a residential building along the railway 139