Nurturing the Young –

Innovation for Sustainability

Events and Activities

Seminar On Unwelcome pressure disturbances from trains in tunnels

Date, time & venue 
2016-08-17;6:00 – 7:00 pm;Room IAS2042, HKUST Jockey Club Institute for Advanced Study Lo Ka Chung Building


Organized by Hong Kong University of Science & Technology (HKUST) - Department of Civil Engineering

And International Association for Hydro-Environment Engineering & Research (IAHR) (Hong Kong Chapter)


Supported by The Hong Kong Institution of Engineers Civil Division (HKIE-CVD)


ABSTRACT: Most passengers on long-haul aircraft are aware that they might experience aural discomfort because of pressure changes during descent from high altitude to ground level – and possibly also during ascent from ground level.  Railway trains tend to remain at ground level so most passengers on them do not expect to experience aural discomfort.  Nevertheless, discomfort would be quite common if railways did not commit significant expense to preventing it.  The potential problem arises because trains induce pressure waves when travelling through tunnels.  The magnitudes of the disturbances increase with the square of the train speed so the phenomenon has increased in importance in recent years.

Analysts of unsteady flows in ducts usually assume unchanging conditions outside passive boundaries.  For decades, so did analysts of unsteady flows in railway tunnels.  However, increases in train speed and economic incentives to minimize tunnel diameters have led to conditions where this happy situation is no longer tenable.  Pressure disturbances radiated from tunnel portals typically increase with at least the cube of the train speed.  They are a significant problem for designers of very high speed railways.

The seminar, which will not include any mathematics, will introduce the causes and characteristics of these phenomena and will discuss a range of measures used to counteract them. In the process, attention will be drawn to uncomfortable lessons experienced by the presenter and others through failure to recognize their ignorance and their consequential extrapolation of inadequate experience.


Prof Vardy is Fellow of various organizations like the Royal Society of Arts, the Institution of Civil Engineers, the American Society of Civil Engineers, the Royal Society of Edinburgh, the Higher Education Academy, and the Royal Academy of Engineering.  He has been Part-time Research Professor in University of Dundee since 1995. His principal current research activities include: minimization of pressure disturbances from railway tunnel portals; evolution of very steep-fronted waves in slab-track and ballast-track tunnels; control of ventilation systems in complex road and rail tunnels and location and removal of blockages in long, subsea pipelines.  He has been the chairman of 10 international conferences, and published almost 200 papers in refereed journals and refereed conferences. His publication includes the textbook on “Fluid Principles” (published by McGraw Hill from 1990 until 2003)




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