# Research on Human Exposure to Transport-Induced Vibration in Buildings
## 5 The Choice of Evaluation Method  
Requirements in national and international standards differ from each other. In the literature on the subject, one can find several attempts to link the value of the crest factor with the selection of evaluation method, as shown below:  
\[CF=\frac{|a_{w}|_{PEAK}}{a_{wRMS}} \tag{5}\]  
where \(|a_{w}|_{PEAK}\) is the maximum peak value in the recorded signal and \(a_{wRMS}\) is the RMS value calculated based on the weighted waveform. In the Polish standard [23], the scope of applicability was dictated precisely by the value of the crest factor. According to the standard, the analyzed vibration waveforms must have a crest factor value less than 9 to use the RMS method. Standard [23] does not specify what happens if the crest factor has higher values. A very interesting reference to the crest factor was introduced in the Australian standard [25]. It provides ranges within which, depending on the crest factor, different evaluation methods should be used, as shown below:  
* If CF < 6, the RMS method should be used;
* If CF \(\geq\) 6 and CF \(\leq\) 9, both RMS and VDV methods should be used, with the final evaluation result determined by the more unfavorable outcome;
* If CF > 9, the VDV method should be used. This approach is not found in any other standards or recommendations. Generally, in a given country, the use of one evaluation method is recommended, for example, in Poland, it is the RMS method [23], and in the United Kingdom, it is the VDV method [22]. Measurements on the real structure were made to examine if the evaluations using the RMS and VDV method differ from each other. The analyzed building is located in Warsaw on 15 Targowa Street. It is a seven-story residential building constructed using traditional masonry technology (Figure 11). The building was erected before World War II. It is situated 5 m from the edge of the roadway and approximately 25 m from the tram line (distance measured from the rail head) and is directly above a metro tunnel. The measurement point in the \"Z\" direction was located in the middle of the ceiling span in a room on the fifth floor on the side facing the roadway. Figure 11: Experimental building “C”. The same events analyzed using the RMS method were also subjected to analysis using the VDV method. The duration of the events, which varied from 14 to 24 s, was taken into account. The results of the VDV method analysis, along with a summary of the HPVI indicators, are shown in Table 4.  
The colors presented in Table 4 indicate the exceedance of the respective threshold lines, i.e., if VDV \(<\) 0.2, there are no complaints (white color), if 0.2 \(<\) VDV \(<\) 0.4, there is a low probability of complaints (yellow color), and if VDV \(>\) 0.4, there is a possible occurrence of complaints (red color). For the HPVI, yellow-marked values mean that the perception threshold of vibration was exceeded, while a red color means that even the comfort level was exceeded. Threshold exceedances in the case of the VDV method analysis occurred for 14 events, with 4 of these exceedances corresponding to potential complaints regarding comfort. The assessment of the impact of different transportation sources on the VDV analysis results indicates that only tram passages caused exceedances of the threshold values for the probability of complaints. At the building on 15 Targowa Street, 19 events were recorded where the threshold for human perceptibility of vibrations, according to HPVI values, was exceeded, accounting for 68% of all recorded events. The ceiling of the room where the measurements were conducted proved to be more sensitive to vibrations generated by surface transport vehicles, mainly terms (see Table 4). In 100% of the recorded tram passages, the threshold for the perceptibility of vibrations was exceeded, and in six events, the requirements for ensuring the necessary comfort for people in this room during the day were violated (35%).