Division Correction for structural radiation (bridges and viaducts)

In the case where the track section is on a bridge, it is necessary to consider the additional noise generated by the vibration of the bridge as a result of the excitation caused by the presence of the train. Because it is not simple to model the bridge emission as an additional source, given the complex shapes of bridges, an increase in the rolling noise is used to account for the bridge noise. The increase shall be modelled exclusively by adding a fixed increase in the noise sound power per each third octave band. The sound power of only the rolling noise is modified when considering the correction and the new L_{W,0,rolling–and–bridge,i} shall be used instead of L_{W,0,rolling-only,i} :

where C_bridge is a constant that depends on the bridge type, and L_{W,0,rolling–only,i} is the rolling noise sound power on the given bridge that depends only on the vehicle and track properties.