Table 2 Rail roughness limits at different speeds
From: Rail Roughness Acceptance Criterion Based on Metro Interior Noise
Speed (km/h) | Rail roughness limit (dB) | ||
|---|---|---|---|
All-wavelength band: 5–315 mm | Sensitive band: 20–63 mm | Common band: 31.5–50 mm | |
40 | ISO +14 dB | ISO +16 dB | / |
50 | ISO +10 dB | ISO +12 dB | ISO +19 dB |
60 | ISO +7 dB | ISO +8 dB | ISO +12 dB |
70 | ISO +5 dB | ISO +6 dB | ISO +10 dB |
80 | ISO +3 dB | ISO +3 dB | ISO +7 dB |
90 | ISO +1 dB | ISO +1 dB | ISO +4 dB |
100 | ISO | ISO | ISO |
110 | ISO −2 dB | ISO −2 dB | ISO −3 dB |
120 | ISO −3 dB | ISO −3 dB | ISO −  dB |