How is the vibration impact determination different from noise impact determination?
Like noise, vibration levels vary with train speed and distance from the track. Unlike noise however, vibration is evaluated against a fixed impact level for a single train pass-by: 80 VdB (vibration velocity level in decibels). A level above 80 VdB constitutes impact based on causing human annoyance. A vibration level of 80 VdB is, however, well below the level that would cause damage to buildings. Further, vibration levels vary depending on ground conditions under the track solid rock transmits vibration better than soft soil.
