Effects of Nocturnal Rail Noise on Sleep - Results of a Field Study in the Cologne/Bonn area.

Abstract

Within a German-French cooperation on traffic research (DeuFrako), mainly funded by the German ministry of economics and the French ministry of transport, in spring 2008 the DLR-Institute of Aerospace Medicine started a 15-month field study examining the effects of nocturnal rail traffic noise on sleep (part of the sub-project RAPS (Railway noise, Annoyance, Performance, Sleep)). In this study altogether 33 subjects were polysomnographically investigated during 9 consecutive nights each. Electrophysiological signals included EEG, EOG, EMG, ECG, respiratory movements and finger pulse amplitude. Three sound level meters (class 1) continuously ineasured the sound pressure level LAS and LAF two metres in fiont of the facade and at the sleeper's ear for every night. In addition, every time the external background level L90 was exceeded by 3 dB, both the external as well as the internal noise was recorded. A meta-analysis of former laboratory sleep studies as well as this field study show that the awakening probability is higher for freight trains than for aircraft and road traffic noise (only part of the laboratory exaininations), which is in contrast to inost of the annoyance studies. However, it could also be shown in this field study tllat the annoyance judgments are mainly fomed during tlle day whereas the night does not essentially contribute to this evaluation.