Optimized Sensors Network and Dynamical Maps for Monitoring Traffic Noise in a Large Urban Zone

Abstract

We review a Dynamap European Life project whose main scope was the design, commissioning, and actual implementation of “real-time” acoustic maps in a district of the city of Milan (District 9, or Z9, composed of about 2000 road stretches), by employing a small number of noise monitoring stations within the urban zone. Dynamap is based on the idea of finding suitable sets of roads displaying similar daily traffic noise behavior, so that one can group them together into single dynamical noise maps. The Dynamap sensor network has been built upon twenty-four monitoring stations, which have been permanently installed in appropriate locations within the pilot zone Z9, by associating four sensors to each one of the six group of roads considered. In order to decide which road stretches belong to a group, a non-acoustic parameter is used, which is obtained from a traffic flow model of the city, developed and tested over the years by the “Enviroment, Mobility and Territory Agency” of Milan (EMTA). The fundamental predictive equation of Dynamap, for the local equivalent noise level at a given site, can be built by using real-time data provided by the monitoring sensors. In addition, the corresponding contributions of six static traffic noise maps, associated with the six group of roads, are required. The static noise maps can be calculated from the Cadna noise model, based on EMTA road traffic data referred to the ‘rush-hour’ (8:00–9:00 a.m.), when the road traffic flow is maximum and the model most accurate. A further analysis of road traffic noise measurements, performed over the whole city of Milan, has provided a more accurate description of road traffic noise behavior by using a clustering approach. It is found that essentially just two mean cluster hourly noise profiles are sufficient to represent the noise profile at any site location within the zone. In order words, one can use the 24 monitoring stations data to estimate the local noise variations at a single site in real time. The different steps in the construction of the network are described in detail, and several validation tests are presented in support of the Dynamap performance, leading to an overall error of about 3 dB. The present work ends with a discussion of how to improve the design of the network further, based on the calculation of the cross-correlations between monitoring stations’ noise data.

Railway Line Occupancy Control Based on Distance Determination Sound Method

“…The results also confirm that the emitted noise is increased with higher speeds too, but while the rolling noise rises with a speed exponent of about 3, the sound emitted by aerodynamic sources rises with a speed exponent of about 6 [38].…”

“…When considering ground-borne noise and vibration from railway vehicles, exposure to human annoyance is often considered [36,37]. All these issues are extremely important, especially in the case of monitoring traffic noise in a large urban area [38].…”

Methodological Aspects of Industrial and Transport Noise Monitoring

“…An important aspect of industrial and transport noise monitoring is noise mapping [40][41][42]. The construction of noise maps, especially those that provide objective monitoring of noise pollution in real conditions with a possible determination of the potential effectiveness of the implementation of a set of measures aimed at reducing noise pollution, is an effective tool to support the adoption of appropriate management decisions [43,44].…”

Management of Noise Pollution

“…Environmental noise modeling has the objective to estimate national and local equivalent noise sound pressure levels in terms of L 90 , L 10 , L max , L min and L eq . The result of noise modeling may be used for the development of two-dimensional (2D) and three-dimensional (3D) noise maps which provide information on noise exposure of people [44,45]. Noise monitoring is used to assess critical sound pressure levels in residential, commercial, and industrial areas under different environmental conditions.…”