Optimum sound reduction index value for gangway constructions of metro trains

The aim of the investigations is the determination of an optimum sound reduction index value for gangway constructions of metro trains. A sound reduction index is considered to be ideal if it guarantees compliance with demanding requirements on the interior noise of metro vehicles whilst taking into account sufficient certainty.On the basis of existing vehicle characteristics, of values for sound power and sound insulation, measured at metro trains and based on a calculation model for the interior noise level the interior sound pressure level is calculated for a typical metro train for a driving speed of 60 km/h. In doing so, the transmission loss of the gangway is varied until the target value of the interior sound level is reached.The target value of the interior sound level is based on the most stringent established requirement on metro vehicles. This value is reduced by 3 dB in order to factor in the forecast accuracy of the calculation model. Furthermore, it is required that the interior sound pressure level transmitted by the gangway construction has to be another 3 dB lower, so that also contributions from the car body are taken into account.Result of the study will be shown.