The redevelopment of a subway station in central London required the removal of a thick concrete slab, approximately 66 x 56 ft. To minimize the potential disruption, our customer JoTech Ltd., a company with over 20 years NVH consultancy experience, was commissioned to estimate the noise that would be generated during demolition.
Measurements were taken using the m+p SO Analyzer software running on a laptop computer, with a four-channel portable USB data acquisition module. The lightweight, easily transportable kit and the flexibility of the software, including integrated narrowband and third-octave calculations, are ideally suited to such on-site investigations. It is estimated that applying this noise prediction technique saved hundreds of thousands of dollars and many weeks of construction time.
The solution devised by JoTech consisted of two parts. In the first, an estimate of the forces imposed on the slab by a mechanical breaker was made using a similar concrete slab located elsewhere in London. In the second part, the noise transfer function NTV from the slab to the critical areas (a nearby foreign embassy and the subway station platform) was measured. This was then combined with the breaker force measurements to estimate the levels of noise that would be generated during demolition operations. With that information, an appropriate demolition strategy was created.
JoTech used m+p international’s real-time analyzer for both breaker force and noise transfer function measurements. Results were available immediately, which enabled JoTech to check their validity and allow for adjustments.
This technique for predicting sound levels during demolition enabled the contractors to restrict costly chemical cracking to one area of the slab while still maintaining the safety and comfort of embassy staff and subway commuters.
Download the 3-page article Novel Noise Prediction Technique for Demolition Saves Time and Money published in the December issue of the Sound & Vibration magazine.