Rolling noise, a major component of disturbance emitted to wayside areas along Shinkansen and existing railway routes, is generated when wheels and rails vibrate due to excitation caused by minor irregularities on their surfaces (Fig. 1). To evaluate rolling noise and promote measures against it, the RTRI developed a technique to estimate such noise based on a theoretical model proposed in Europe.

To investigate the phenomena involved in the mechanism that causes rolling noise, the RTRI analyzed the distribution of irregularities on wheel and rail surfaces and the vibration and acoustic characteristics of these components through field tests and numerical calculations. Based on the analytical results thus obtained, the RTRI established vibration and acoustics element models each corresponding to a phenomenon, which were combined to constitute a technique for the estimation of rolling noise.

The RTRI evaluated this method for precision by implementing running tests in a Shinkansen section and three sections of existing railway lines. The tests showed close agreement between the estimated and measured values, indicating an average difference of 1 dB or less and a standard deviation of difference of 3 dB or less (Fig 2 (a)). It was also proved that the major components of rolling-noise disturbance were the noise emitted by the rail at 500 to 1,600 Hz and that from the wheel at 2,500 Hz or over (Fig 2 (b)).

The RTRI plans to apply this technique to the development of rolling noise prevention measures.