Acoustics case study
PAVA Design at Crossrail’s Bond Street Station
SRL Technical Services Limited were commissioned by Costain Skanska JV to assess the acoustic performance of the ‘Public Address / Voice Alarm’ (PAVA) system in the Bond Street Station for the new Crossrail line.
The critical feature of the PAVA system is that the message being delivered must be intelligible (i.e. the public can clearly hear what is being said). For this reason the Crossrail contract requires a minimum Speech Transmission Index (STI) of 0.5 to be achieved in all public areas.
We developed detailed computer models of all public areas of the station to calculate the STI in accordance with BS EN 60268-16:2011 ‘Sound system equipment Part 16: Objective rating of speech intelligibility by speech transmission index’. The areas assessed included the Platforms and Tunnels, Eastern Ticket Hall, Western Ticket Hall and Link Tunnels. We used our models to map the STI and SPL coverage throughout these areas and identify non-compliance with Crossrail’s PAVA performance criteria.
In areas where the PAVA performance criteria were not achieved, we worked closely with the design team to improve the performance of the PAVA design. This included modifications to the speaker specifications and locations, and also changes to the architectural design, e.g. incorporating additional acoustic absorption to shorten the reverberation time.