DYNAMAP project: Procedure for noise mapping updating in urban area

The main goal of Dynamap project, as for the urban case study, is to produce a dynamic noise map within a given area of the city of Milan containing about 2000 road arches, by using 24 continuous measuring stations. This map will be dynamically updated at an interval varying from 5 minutes to 1 hour. The reliability of the mapping process for a complex urban context is related to the fact that the vehicle flow patterns are supposed to be very regular, in function of the use of different roads. In the first phase of the project, nearly 100 road arches have been monitored for a period of at least 24 hours and have been statistically aggregated in two clusters, depending on their noise level profiles. Then the analysis of the distribution of a non-acoustic parameter -which depends on the vehicular flows- Allowed to attribute a specific noise profile to a road not present in the database. The total amount of road arches has been finally divided into six groups to better distinguish the different noise trends. Four monitoring stations have been planned to be installed for each group, selecting the most representative arches. For each group of roads, a basic noise map covering all the pilot area has been calculated with an acoustic software. In this paper the procedure for the updating of the pre-calculated basic noise maps in the starting operational phase of Dynamap is discussed. The process is based on the average of the noise level variations calculated at the monitoring stations, according to two different procedures. The absolute equivalent noise level at a certain time interval for an arbitrary receiver point in the urban pilot area can be obtained by properly summing the six acoustic maps updated values.