Crossrail is the new high frequency, high capacity railway for London and the South East. It is one of Europe’s largest railway and infrastructure construction projects.
Liverpool Street station is the deepest point on the Crossrail route, sitting 50 metres beneath the City of London. The development includes two new ticket halls – one newly constructed beneath Liverpool Street while the other is formed from the redevelopment of Moorgate station.
Sandy Brown was engaged to provide consultation on:
- control of noise egress from mechanical and ventilation plant
- architectural acoustic design of internal areas including ticket halls and concourses
- 3 Dimensional computer modelling of reverberation and speech intelligibility.
Special acoustic features
The key aspects of the acoustic design were the provision of suitable conditions within the internal areas for speech intelligibility of the public address and voice alarm systems and the control of noise egress from the significant amount of cooling and ventilation plant, in particular the Tunnel Ventilation Fans.
ODEON computer modelling software was undertaken to inform the development of the design by the Architects and Public address and voice alarm system designers. The computer model was used to predict the reverberation time and speech transmission index to allow assessment against the specified performance requirements and inform the location and extent of sound absorbent treatment. The areas modelled included Moorgate and Broadgate ticket halls, the central concourse, platforms and escalator shafts.
The extensive plant and very large tunnel ventilation fans required significant attenuation measures to achieve suitable external noise levels at nearby noise sensitive buildings. To provide sufficient control of noise from the tunnel ventilation fans required a design incorporating both acoustically lined plenums, in addition to, sizeable proprietary attenuators.