New voice alarm systems for underground stations developed through use of acoustic simulation techniques and novel engineering solutions.
Submitting InstitutionLondon South Bank University
Unit of AssessmentGeneral Engineering
Summary Impact TypeEconomic
Research Subject Area(s)
Information and Computing Sciences: Artificial Intelligence and Image Processing
Psychology and Cognitive Sciences: Cognitive Sciences
Studies In Creative Arts and Writing: Performing Arts and Creative Writing
Summary of the impact
This Case Study demonstrates how research has benefitted a commercial
company (Telent Ltd), a public sector organisation (London Underground Ltd
(LUL)) and the safety of staff and 1.4 billion passenger journeys.
The research enabled Telent to:
The Acoustic Research Group at London South Bank University (LSBU) has
undertaken research into room acoustic computer simulation since 1993, and
specifically, into non-diffuse enclosed spaces in public and industrial
environments. Underground station platforms are an example of a
non-diffuse enclosed space where speech intelligibility is of paramount
importance both for service announcements and passenger safety.
This impact case study is underpinned by research carried out from 1993
to 2001 by Professor Bridget Shield (Professor of Acoustics, LSBU) and Dr
Stephen Dance (Research Fellow, LSBU). It was funded mainly by grants from
the EPSRC [GR/H82556/01, £100,729; 1993-6 and GR/L20894/01; £129,669,
Research into computer models for the prediction of sound in enclosed
spaces led to the identification of novel algorithms and to an
image-source code that could simulate sound pressure and predict the
effects of interference on the sound field . Further refinement of the
model enhanced its ability to simulate and predict the effect of noise
control techniques on temporal as well as spatial room acoustic parameters
An alternative modelling technique for room acoustic computer simulation
based upon ray-tracing demonstrated that where the treatment is located is
just as important as how much absorption is fitted in the room . This
model was experimentally validated in a room configured in multiple ways
to predict the effect of absorptive treatment on the temporal sound field.
The findings from this study were recognised as having implications for
reducing material and installation costs. A method to correct standardised
absorption coefficients so that the data is consistently adjusted for use
in computer modelling, specifically where absorption coefficients exceed
one, was also developed.
The above mathematical models were further refined (1994-2001) to predict
speech intelligibility and were targeted towards underground platform
prediction , the primary differences between the respective models
being multiple loudspeakers and curved surfaces, typically found in all
underground transportation systems.
The accuracy of the above models was verified on London Underground Ltd
platforms  and on the new Hong Kong Metro . Innovative and practical
VA system design guidelines were informed by these results.
To reduce the complexity of the simulations, a simplified modelling
methodology was developed in 2003  by Dr Stephen Dance. A web
browser-based version was subsequently produced by Dr Dance (2009) under a
Schultz Research Grant (Acoustical Society of America: US$3000 2008-9),
the output from which provided tools for modelling any large enclosed
space such as auditoria, classrooms, open plan offices, factories, atria,
metro systems, arenas and sports stadia, as well as underground transport
References to the research
 S. Dance, J. Roberts, B. M. Shield. Computer prediction of sound
distribution in enclosed spaces using an interference pressure model,
Applied Acoustics, 44, 53-65, 1995. (Doi: 10.1016/0003-682X(94)P4419-7)
 S. Dance, B. M. Shield. The complete image-source method for the
prediction of sound distribution in non-diffuse enclosed spaces, Journal
of Sound and Vibration, 201(4), 473- 489, 1997. (Doi:
 S. Dance, B. M. Shield. The modelling of sound fields in enclosed
spaces with absorbent room surfaces. Part II - Absorbent Panels, Applied
Acoustics, 61(4), 373-384, 2000. (Doi: 10.1016/S0003-682X(00)00011-6)
 L. N. Yang, B. M. Shield, Development of a ray tracing computer model
for the prediction of the sound field in long enclosures, Journal of Sound
and Vibration, 229(1), 133-146, 2000. (Doi:10.1006/jsvi.1999.2477)
 L. N. Yang, B. M. Shield, The prediction of speech intelligibility in
underground stations of rectangular cross section, J. Acoust. Soc. Am.,
109, 266, 2001. (Doi: 10.1121/1.1329617)
 S. Dance, Minimal input models for sound level prediction in fitted
enclosed spaces, Applied Acoustics, 63, 359-372, 2002. (Doi:
Details of the impact
This Impact Case Study relates to research that has had a beneficial
economic impact on an international engineering company (Telent), led to
an improved service provision for a public sector organisation (LUL) and
made using stations on the London Underground safer for both LUL staff and
the travelling public.
The 7/7 bombings on the London Underground in 2005 caused a reappraisal
of evacuation standards and guidance. LUL issued new requirements (2006)
for Public Address/Voice Alarm (PA/VA) systems to facilitate the efficient
evacuation of stations. Particular emphasis was placed on electro-acoustic
performance on deep platform stations as these are the most difficult and
challenging to evacuate. In response to the new requirements, a major
refurbishment of all PA/VA systems on London Underground was initiated by
Transport for London (2006).
Telent (formerly Marconi) was awarded the contract (2006) to refurbish 74
stations on three underground lines (Jubilee, Northern and Piccadilly
(JNP)). Telent recognised the need for specific technical expertise and
selected the Acoustics Group at LSBU as their technical partner because of
the Group's reputation and expertise in acoustic modelling and
specifically, in measuring and predicting performance of PA/VA systems in
underground stations. The Head of Engineering (Metro) at Telent reported
to independent consultants that Telent would not have been successful in
this project without the support of LSBU [1, 2].
LSBU and Telent successfully applied for a Knowledge Transfer Partnership
(KTP) award (2008- 10; £187k) to facilitate their collaboration .
In 2010, Telent selected the resulting room acoustic modelling software
based upon LSBU's research and further refined this through the KTP, to
model the acoustics in complex underground stations, including the 74
stations. This led to the optimisation of PA/VA design parameters. The
adoption of this model and approach resulted in significant time and
development costs savings for the Company, estimated at £500k [1, 2].
During 2010-11, the final PA/VA designs produced by Telent and based upon
the LSBU model were installed and commissioned by Telent engineers in the
74 underground stations. LUL had accepted all 74 installations by 2012.
The gain on each of the 5000 associated loudspeakers was set at the design
phase such that the load on each loudspeaker was minimised, saving an
estimated 11 MWh of electricity (£2000/per year) in each deep sub-surface
station (~35). The overall saving in electricity costs to LUL amounted to
approximately £70k per annum [1, 2].
Telent considered LSBU's research to have been crucial in enabling it to
deliver the system upgrade on time and to budget, and to avoid potentially
steep penalty costs through late delivery. The PA/VA upgrade project has
delivered a net profit of £300k to Telent. In addition, the Company has
gained the maintenance contract for the new PA/VA system worth £1.5M. The
Head of Engineering (Metro) at Telent has stated that, "We now have a PA
system that provides far greater security to travellers on the
Underground" [1, 2].
Telent has also successfully bid for further PA/VA installation projects
at Whitechapel, Liverpool Street and Charing Cross stations. As a direct
result of its success, Telent recruited 5 new professional level jobs
during the project including one permanent job [1, 2]. In addition,
Telent's technical team (6 staff) have received CPD training from LSBU in
acoustics, the first within Telent Ltd, with two members of the team going
on to gain Masters degrees from LSBU in 2011 .
The PA/VA system was found to be so improved that light classical music
can be played in ticket halls. In 2012, for the first time, oral
advertisements were delivered in underground stations e.g. featuring Boris
Johnson promoting the London Olympics (July 2012), and Barbara Windsor on
Poppy Day (November 2012) .
LSBU's research and the KTP outcomes have contributed to the development
of a new speech intelligibility scale in the 2011 revision of the IEC BS
EN 60268-16 Standard (4th edition, 2011) . In
addition, the KTP Associate Luis Gomez-Agustina won the Institute of
Acoustics, Peter Barnett Student Award 2013 as a result of this work .
Furthermore, since 2010, 1.4 billion passenger journeys have been made
safer as a result of the improved PA/VA system on the London Underground
Sources to corroborate the impact
 Report of independent consultants (The Innovation Partnership, 2013)
- covers interview with Head of Engineering (Metro), Telent Ltd. Contact:
Managing Director, The Innovation Partnership (firstname.lastname@example.org).
 Contact: Head of Engineering (Metro), Telent Ltd.
 KTP 006293 Grant Award and Final Report - both available on request
 Contact: Head of Engineering (Tube Lines Ltd). NB: Tube Lines are the
company which provide maintenance services for trains and infrastructure
on the Jubilee, Northern and Piccadilly lines)
 IEC BS EN 60268-16 - Sound system equipment: Objective rating of
speech intelligibility by speech transmission index (4th edition, 2011).
 Institute of Acoustics, Peter Barnett Student Award 2013, www.ioa.org.uk/medals-and-
awards. - Award to L Gomez-Agustina, KTP Associate on the Telent