Road traffic noise emissions depend on source strength and propagation factors. During night time and under certain topographical conditions special effects can occur both on the source side and regarding sound propagation. Up to now many of these factors cannot be accounted for and are thus ignored in calculations. As the night time period is relevant for legal consideration in many cases it would be important to lower the incorporated uncertainties.
Investigation and quantification of influence factors on road traffic noise emissions specific for night time periods: car fleet, vehicle speed, driving conditions, distribution on lanes and meteorological conditions. In addition the relevance of sound propagation in valleys will be characterized.
Development of an empirical model to estimate the significance of the influence factors in a quantitative manner and formulation of a simple method for practical applications.
Phase I: Definition of relevant measuring points
Evaluation of appropriate pilot-measuring points in the area of a high-performance road, the information about traffic volumes, speed, track allocation and possible information about meteorology could be provided.
Phase II: Metrological recordings
Receiving the acoustic noise pollution road with determination the data defined above. The aim is to establish a correlation between the above-identified factors and the acoustic emissions for each geometry. For the investigated geometries calculations are performed and demonstrated the differences. The results of the pilot measurements are intended to provide guidance for defining the main measurements.
Phase III: the main measurements
From Meteo statistics can be derived statements about the annual average importance. The specified data to be collected, evaluated accordingly and to consider the correlation with meteorological and other factors for each measuring point.
Phase IV: Evaluation
In parallel with the metrological studies computer simulations are carried out on the importance of factors. The calculations are carried out with analytical approaches and numerical theoretical models.
The outcome is an empirical model for practical application on how to handle the special effects of traffic noise emisions occurring during nights in order to improve accuracy of road traffic noise emission calculations.
Improving of transport street noise model with assessment of the transport noise during the night.
Assessment of the noise is an important base for the application of measures decreasing the negative impact of transport.