A practical methodology for impact assessment of tunnel boring machine generated noise

Tunnels are a vital part of many on-going and planned infrastructure projects in Hong Kong. The use of Tunnel Boring Machines (TBMs) to construct tunnels is increasing in congested areas in Hong Kong to minimize the disruption to surface traffic. Although the TBM method is superior to other tunnel construction techniques in many aspects, its use may cause noise nuisance to local residents. Therefore, there is an urgent need for a systematic methodology to assess the noise impact caused by its operation so as to formulate effective strategies to mitigate any potential ground and structural borne noise nuisance to locol residents. Detailed development of a practical assessment methodology on the basis of wave propagation through multiple media is presented in this paper. The methodology can be used to gain a better understanding of the transmission mechanisms of the noise from the operating TBM to the receiver and to predict the level of noise so perceived. Results of the assessment will provide a viable basis for Government regulators, engineers and contractors to make proper decisions on the design, construction method, construction equipment and mitigation measures during the feasibility study and detailed design stage of a project so as to minimize undue noise impact to the public.