Evaluating Methods of Whole-Body-Vibration Exposure in Trains
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This paper studies the whole-body vibration in trains which constitutes one aspect of the physical environment that can cause discomfort to passengers. Modern methods of assessment use digital techniques. Accelerometers are usually mounted on the seat pan, the backrest and floor (although occasionally it is necessary to measure solely on the floor for standing passengers). Depending on the location, direction and standard to be used, a different method of signal processing and scaling is used for each accelerometer. Data are frequency weighted in order to model the human response to vibration in that location and direction. The most commonly used weightings are Wk, Wd, Wb and the Sperling filter, B(f). The root-mean-square (r.m.s.) is the basis for most assessments of railway vibration. However, it is also possible to measure the vibration dose value (VDV) and the maximum transient vibration value (MTVV) in performing assessments according to ISO 2631-1. When undertaking assessment in accordance with ISO 2631-4 , a statistical method may also be used. Several criteria systems have been defined to assist users in interpreting results. These include tables of overlapping ranges of magnitudes (ISO 2631-1) and thresholds (e.g. Sperling’s method). According to these criteria, previous measurements of vibration in trains have established that it is not usually considered severe, but, at worst, “strong, irregular, but still tolerable” or “a little uncomfortable”.
- 2010 fascicula14 nr2