Through extensive vibration surveying at the site and within adjacent buildings, RBA established that overground train movements on the viaduct were likely to give rise to levels of re-radiated noise that were higher than commonly adopted standards though as the predicted levels were not excessive we researched a bespoke, “secondary” form of vibration mitigation to reduce vibration levels entering the building.
RBA proposed the ground level slab be cast on a semi-resilient material and that the upper most sections of the nearest piles be resiliently sleeved with acoustic material. This was a significantly more cost effective solution than full building isolation which successfully resulted in acceptable re-radiated noise levels in the completed building.
The site comprised two residential blocks adjacent to two ground-borne vibration sources – (1) a viaduct with rail lines connecting London Bridge to Waterloo East and London Blackfriars Stations and (2) LUL Jubilee Line tunnels linking London Bridge and Southwark underground stations. Hence the initial concern was raised over the levels of ground-borne vibration incident on the proposed structures.
Mount Anvil had been advised previously (by others) that full building isolation measures would be necessary but they were reluctant to pursue this route for cost reasons so engaged RBA Acoustics as their acoustic consultants to conduct further survey works.