# Influence of the Analytical Segment Length on the Tram Track Quality Assessment
## 4 Discussion  
The distribution of calculated values of the W and J indices along the Osijek tram network confirmed that the tram-track geometry quality depends on exploitation intensity and is significantly influenced by the type of rail fastening, curvature of the alignment, and position of the tracks in the urban network. Most of the analytical track segments not constructed with the discrete double-elastic rail fastenings showed insufficient track geometry quality. Furthermore, on sections with the same tram-track construction type and exploitation intensity, the tram-track geometry quality was poorer on the analytical segments in the curves of small radii than the ones located in the straight line. Finally, the analytical segments along intersections or stops showed faster track-quality degradation than those not affected by road traffic. By comparing distributions of W and J values over track sections for the same analytical segment length, similarities in the behavior of both indices were observed (Figure 9). The relations between the W and J index values calculated for the same analytical segment are presented in Figure 10. The decrease in the analytical segment length causes the grouping of segments with extreme values of the W (0.0 and 1.0), while at the same time, the J value uniformly decreases. By analyzing the change in the track geometry quality depending on the analytical segment length, it was noticed that the change in the segment length has a different effect on the value of the calculated W index than on the value of the calculated J index (Figures 7 and 8). Track geometry quality defined by the W index changes as the length of the analytical segment decreases. For example, individual shorter analytical sub-segments, which belong to the same 200m analytical segment, progressed to poorer track quality (larger W value). In contrast, the remaining sub-segments progressed to better track geometry quality (smaller W value) than the corresponding 200m analytical segment. However, by reducing the analytical segment length relative to the 200m length of the segment, the value of the J index on individual shorter sub-segments was less than or equal to the value of the J index of the corresponding 200m analytical segment. To obtain more information on what happens to the W and the J indices values with the change in the  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**TQI**} & \multirow{2}{*}{**Quality/Value**} & \multicolumn{4}{c}{**Analytical Segment Length**} \\ \cline{3-6}  & & **200 m** & **100 m** & **50 m** & **25 m** \\ \hline \multirow{3}{*}{W} & Good & 35.2\% & 38.1\% & 39.3\% & 41.1\% \\  & Sufficient & 25.4\% & 21.4\% & 22.1\% & 21.0\% \\  & Insufficient & 39.4\% & 40.5\% & 38.7\% & 37.9\% \\ \hline \multirow{3}{*}{J} & \textless{}2 mm & 43.2\% & 49.4\% & 53.7\% & 61.9\% \\  & \textless{}4 mm & 21.9\% & 19.3\% & 26.0\% & 25.2\% \\ \cline{1-1}  & \textgreater{}4 mm  
analytical segment length, the average, maximum, and minimum values of the calculated indices, depending on the length of the analytical segment, were compared to the value of the corresponding calculated index values for the 200m-long analytical segment. The results are shown in Figure 11.  
Compared to the W value of the corresponding 200m long segment, the average value of the W index on shorter sub-segments remains unchanged. On the other hand, reducing the analytical segment length increases the maximum W value while the minimum W  
Figure 11: An influence of analytical segment length on the W and J index values. Figure 10: Relationship between the W and J indices values. value decreases. In other words, a decrease in the length of the analytical segment along 200 m of tracks will increase the value of the W index on a few sub-segments, while on the remaining sub-segments, there will be a decrease in the value of the W. The average value of the W on the short sub-segments will be relatively equal to the W value on the corresponding 200m-long segment.