Annoyance and self-reported sleep disturbances due to structurally radiated noise from railway tunnels

In Norway, the requirement for structure borne noise from tunnels is LpAFmax = 32 dB inside dwellings. According to the Norwegian Standard 8175 it is expected that up to 20% of the exposed population are disturbed by the noise at this level. However, the scientific basis for this noise limit is poor. The aim of this study was to determine the degree of annoyance and self-reported sleep disturbances as a function of LpAFmax. In the present study, 521 dwellings exposed to structural sound from railway rock-tunnels were identified. A questionnaire was sent to one randomly selected person above 18 years of age from each dwelling. The results showed that both noise induced annoyance and reported sleep disturbances were significantly related to LpAFmax. Other factors that increased the annoyance were high pass-by frequency of freight trains per day, and degree of sound insulation of the windows. At LpAFmax = 32 dB, 20% were slightly or more than slightly annoyed, and 4% were moderately or more than moderately annoyed. According to the pre-existing assumption that up to 20% of the exposed population are disturbed by the noise at this level, the present results give support to the Norwegian noise limit LpAFmax = 32 dB inside dwellings of structure borne noise from railway tunnels.