Do current guidelines on vibration provide sufficient health protection at the community level independent of the accompanying soundscape?
Graz University of Technology
Monday 1 june, 2015, 17:20 - 17:40
0.4 Brussels (189)
The introduction of new types of tramways in the city of Graz (Austria) resulted in strong complaints from local residents in certain areas of the city. Pilot vibration measurement observed some increase in one area where the geological conditions favoured propagation. However, no consistent pattern were found which could explain also the raise in complaints from other locations. To better understand the underlying reasons for the complaints a systematic measurement exercise was designed for 5 locations and combined measurements for vibrations and sound were conducted from 8pm to 8am by means of a dummy head measurement system HSU III.2 in combination with a SQuadriga II mobile recording system (HEAD acoustics GmbH). We observed significant differences in both acoustic and vibrations exposure levels at the 5 locations. An overall systematic difference between "old" and "new" tramways was not detectable with standard acoustic indicators. All measured vibration levels (Wm weighted) remained below the standard (ÍNORM S 9012). On some locations nearly no relevant spread were observed - while larger spread was found on other locations. Further analysis showed a strong underestimation of the acoustic feature by the A-weighting (C-A > 20 dB). Furthermore, the required slow weighting (ÍNORM S 9012) showed significant underestimation of the actual perceived vibration exposure. Eventually, some of the psychoacoustic parameters (tonality, roughness, sharpness) did indicate slight differences between the types of tramways. We discuss whether these overall mixed and confusing results make sense in a combined sound and vibration assessment perspective.
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