Uncertainties in long-term road noise monitoring including meteorological influences

Results from measurements of road traffic noise at large distances depend strongly on the meteorological propagation conditions, i.e. wind direction, wind speed and the atmospheric stability. For the HARMONOISE project long-term measurements at distances ranging from 25 to 1200 m from the highway have been carried out, including the measurement of meteorological parameters employing a 3D ultrasonic anemometer. These parameters cover the three-dimensional wind speed, the wind direction, the vertical impulse flux as well as the Monin-Obukhov length to characterize the atmospheric stability. The measured data were analyzed for different propagation parameters grouping the measured data into classes as a function of the Monin-Obukhov length and wind speed, and the uncertainties for these classes were determined according to the guideline of uncertainties of measurements (GUM). The analysis covers the overall levels as well as frequency structure (transfer function) in 1/3-octave bands.