The principal method for mitigating underground noise and vibrations in the Washington Metropolitan Area Transit Authority's (WMATA's) Metrorail system has been floating slabs. One type of polyurethane isolator pads supporting the floating slabs has been defective, however, and about 18,000 track-ft of floating slabs has settled unevenly, causing operation and maintenance problems. In seeking an alternative method for mitigating underground noise and vibrations, WMATA conducted an in-service testing program of vibration-attenuating rail fasteners in 1983 under Federal Transit Administration (FTA) sponsorship. The fastener tested, which is manufactured by Clouth of Cologne, Germany, is known as Cologne egg. The testing results indicate that the Cologne egg fasteners can yield vibration attenuation up to 8 dB, a moderate reduction yet one that is adequate for certain locations. A set of specifications was then developed for vibration-attenuating rail fasteners by De Leuw, Cather & Co., WMATA's general engineering consultant. The testing program under the contract specifications was successful. Accordingly, about 11,000 units will be procured for new construction. With the egg-shaped rail fastener, WMATA not only has found an alternative method for mitigating underground vibrations, but also has saved $3.5 million in the new construction by replacing the floating slabs with egg-shaped fasteners in the areas where moderate vibration mitigation is required.


  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 75-82
  • Monograph Title: Environmental issues: energy, water, noise, waste, and natural resources
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00711766
  • Record Type: Publication
  • ISBN: 030906113X
  • Files: TRIS, TRB
  • Created Date: Sep 18 1995 12:00AM