Maximum-level as an additional criterion for the assessment of railway noise at night: Derivation of a wake-up protection criterion for standards and regulations

Kurzfassung

On behalf of the Hessian Ministry of the Environment in Germany, an expert report was prepared to clarify if a maximum level distribution of rail traffic noise at night is more suitable to develop a noise protection concept rather than considering the Equivalent Continuous Sound Level LAeq. In this paper, it is shown that a LAeq alone is not sufficient to adequately describe the noise-induced fragmentation of sleep structure and the strongest physiological response to noise at night, the awakening reaction. At sleep, human beings react to individual events, which are mainly characterized by the number of trains, the maximum level distribution and the train type. These measures are not adequately reflected by the LAeq. This paper pursues the principle of minimizing acute effects (awakening reactions, reported sleep disturbances and annoyance) so that short-term (fatigue and increased risk of accidents on the following day) and long-term consequences (risk increases for the onset of diseases) do not occur. Analyzes were carried out by means of polysomnographic data being measured in the field study DEUFRAKO / RAPS considering 33 residents à 9 nights each, all living near busy railway tracks in the Middle Rhine Valley. Results were used to determine an exposure-response function for the awakening probability due to a single train noise event TNE. The sum of the awakening probabilities for all individual events result in the additional train noise induced awakening reactions, which are to be limited in a night-time protection concept. Considering these results together with criteria as derived from survey data on reported sleep disturbances (see Schreckenberg et al.), Möhler et al. will present a combined protection concept for residents affected by train noise at night at this EuroNoise conference. Basic acoustical input data for this concept include maximum level distributions for freight and passenger trains.