Five Years' Monitoring Data on Rail Damper Performance

Roughness in rail surface accumulates with train operations and grows faster on curved tracks than tangent tracks. Higher roughness leads to higher noise radiation. In Hong Kong, railway noise prediction includes a 3dB correction for rail surface deterioration. Depending on rate of deterioration, different rail grinding cycles (typically between 3 and 24 months) are scheduled to ensure train operations without excessive noise radiation. Before rail dampers installation, noise levels were monitored for 1.5 years and around the noise limit with variation +/- 3dB(A) due to rail roughness variation. After installation of rail damper, railway noise was generally maintained at 7dB(A) below the noise limit with variation +/-1.5dB(A) for more than 3 years. Noise reduction at dominant frequencies 630 Hz and 800 Hz were more than 10dB in 1/3 Octave analysis. The rail dampers were installed at alternative spaces such that additional rail dampers can be installed to double the amount in case further noise reduction is required. This paper examines the five years' monitoring data in detail, showing the noise levels with smaller variations over grinding cycles after rail damper installation, and explores rail damper potential ability to slow down the growth rate of rail roughness levels.