Some residents near a highway bridge in Kashiba-cho, Nara complained about noises of house fittings and physical effects that may have been caused by infrasound. Preliminary measurements revealed infrasound of 90 dB or more near the bridge. A series of measurements were thus made near the bridge to determine the source and it was found to be an eigen-oscillation of the bridge girder. The reasons are: (1) signature of bridge-girder oscillation is very similar to that of sound pressure beneath the bridge; and (2) distance-attenuation of sound pressure at 4.8Hz, which is the target frequency, is inversely proportional to the distance from the bridge suggesting the bridge girder to consist a dipole source, i.e. generation of positive and negative pressure on the upper and lower sides of the floor-slab of the girder or vice versa through bending oscillation of the girder. In this article the generation mechanism of infrasound is examined using existing data that are not necessarily perfect for the purpose of rigorous analysis. For the covering abstract see IRRD E104312.


  • English

Media Info

  • Features: References;
  • Pagination: p. 329-34

Subject/Index Terms

Filing Info

  • Accession Number: 00790198
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0-9622072-3-3
  • Files: ITRD
  • Created Date: Apr 11 2000 12:00AM