Directivity of Train Noise in the Vertical Plane

Results from field measurements show that train noise exhibits a vertical directivity pattern. Measurements were made for track at grade and track on an elevated viaduct. Both sets of results showed that train noise increased with the angle of elevation, by about 6 dB(A) when the angle of elevation increases from 8° to 30°. A modified train noise model is proposed which could account for the observed vertical directivity pattern as well as matching the train noise profile.