The piling hammers are the dominant source of noise from the ALBEF site and are in most cases the primary cause of noise complaints. It is essential to demonstrate that best practicable means (BPM) is being implemented and reviewed appropriately.
Due to the size and mobility of this equipment and location near to tall buildings, it is practicably impossible to mitigate the piling works using traditional mitigation measures such as acoustic enclosures and barriers, and quieter piling techniques such as push and bored piling have been ruled out on engineering grounds.
The characteristics of the noise and nature of the equipment made it difficult to identify where exactly the main source of noise is coming from. Therefore, shortly after piling works commenced the FLO noise team took the initiative to bring in specialist acoustic camera equipment from two different suppliers to investigate the sources of noise.
Acoustic cameras can provide a visual representation of sound direction and amplitude. Acoustic cameras have been used successfully in the motor industry and for industrial noise sources such as factories.
They have not however, as far as we are aware, been used before to assess noise from construction sites. Acoustic cameras use a large array of microphones and processing power to instantaneously determine the direction and amplitude of sound and overlay a video image with colour contours. The results of this can be seen within the attached imagery.
It allowed us to pin point the source of the noise and apply focused mitigation to the piling methodology. It also allowed us to pin point weak points within the hammer structure which we can feed back to the manufacturer.