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The wayside noise around a tunnel portal of Shinkansen railway lines mainly consists of both the noise radiated from the tunnel portal and that from an open section. This suggests that the wayside noise around the portal tend to be greater. In order to reduce the noise round the portal effectively, it is necessary to understand the acoustic behavior around the portal and to estimate the contributions of both noise components appropriately. In past studies, the model to predict the noise around the portal for high speed trains, in which both the road traffic noise prediction model (ASJ RTN-Model 2013) and Shinkansen noise prediction model are combined. The predictions with this model tend to be overestimate, although the overall trends are well-predicted. In this study, in order to investigate the distribution of the noise around a tunnel portal, the noise measurement has been carried out. It is found that the noise from the portal is radiated strongly in the direction of approximately 45 ° to the portal and that the contribution of the noise to the total noise is much smaller at a distance of about 80m from the portal. In addition, the laboratory experiment using the scale models has been carried out in order to investigate the contribution of both the noise radiated from a tunnel portal and that from an open section. It is found that, at the measuring points near the portal, the noise from the portal has much greater contribution to the total noise. And, it is also found that the noise is screened due to the vehicle at the open section. Then, the prediction model is proposed, in which the screen effect due to the vehicles at the open section is included. It is found that the prediction show good agreement with the measurements obtained in the experiment.
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