Perforated exit regions for the reduction of micro-pressure waves from tunnels

Honglin Wang, Alan E Vardy, Dubravka Pokrajac

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)
7 Downloads (Pure)


The effectiveness of long, perforated exit regions in reducing pressure disturbances from railway tunnels is assessed. Such disturbances always occur, but their amplitudes are usually small. For the particular case of high speed trains, they can reach levels that would cause annoyance in the absence of suitable counter-measures. This risk is especially large in the case of long tunnels. The mechanisms causing the disturbances are described and the potential effectiveness of perforated exit regions as a counter-measure is demonstrated. It is shown that the effectiveness is sensitive to the number, size and distribution of pressure relief holes along the exit region, but that the most important parameter is the combined area of all of the holes. This parameter controls the balance between external disturbances alongside the perforated region and disturbances beyond the exit portal. It is also shown that the amplitudes of the external disturbances are strongly dependent upon the amplitude and duration of wavefronts arriving at the exit region as well as upon their steepness. This contrasts with the behaviour found for tunnels with simple exit portal regions.
Original languageEnglish
Pages (from-to)139-149
Number of pages11
JournalJournal of Wind Engineering and Industrial Aerodynamics
Early online date25 Sept 2015
Publication statusPublished - Nov 2015

Bibliographical note

The authors are grateful to the following bodies that provided financial support for the project: (i) China Scholarship Council (20117 00029), (ii) National Natural Science Foundation of China (Grant no. U1334201) and (iii) UK Engineering and Physical Sciences Research Council (Grant no. EP/G069441/1).


  • rail tunnel
  • micro-pressure wave
  • perforated exit region
  • pressure gradient
  • wavefront steepness
  • counter-measures
  • sonic boom


Dive into the research topics of 'Perforated exit regions for the reduction of micro-pressure waves from tunnels'. Together they form a unique fingerprint.

Cite this