## 5 Case Studies
### Application to Citywide Transfer Analysis  
In this section, the authors used GIS data to investigate the citywide transfer characteristics in Shenzhen. The average transfer time is been regarded as one of the most important performance indexes to evaluate the efficiency and reliability of a public transport network. However, it is quite difficult to calculate accurate average transfer time because the traditional methods cannot recognize each passenger's transfer trip in practice. Alternatively, the authors have presented the dynamic station-specific elapsed time threshold to recognize transfer trips and measure the transfer performance of public transportation systems for a city. To further explore the characteristics and profiles of passenger metro-to-bus transfer behavior in Shenzhen, this study has completed estimating the weekday morning-peak-hour elapsed time thresholds of total 131 metro stations belonging to five metro lines based on the huge training dataset at 7:00-9:00 from 11 March to 15 March 2019, which were calculated within no less than 16 min. Statistically, it is found that the elapsed time thresholds of all stations vary in the range of 18-39 min, and the corresponding network-level average transfer time threshold is about 27 min. Over 52.67% of the thresholds range from 22 min to 30 min, and about one third of them (32.06%) exceeds the threshold of 30 min. Furthermore, the remaining (15.27%) are below 22 min. Briefly, the results show that local transit agencies should focus more on transit network connectivity improvements between metro and ground-level buses for attracting ridership by decreasing transfer time. Figure 10 summarizes the distribution of metro-to-bus transfer elapsed time threshold estimated by the proposed method in this paper under scenario S1, which includes 131 metro stations belonging to metro lines 1-5 in Shenzhen. The results demonstrate that those metro stations with poor connectivity to their feeding ground-level bus stations are scattered all over the city, but are concentrated more in the central areas, such as Luohu District and Futian District. The authors have also conducted a field survey at four metro stations with poor connectivity to nearby bus stations for validation, including Science Hall Station, Shopping Park Station, Cheognmiao Station, and Shenzhen North Station. The estimated elapsed time thresholds of Science Hall Station, Shopping Park Station, and Shenzhen North Station are about 37 min, and that of Cheognmiao Station is 38 min. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Scenario** & **S1** & **S2** & **S3** & **S4** & **S5** & **S6** \\ \hline Guomoa & 25 min & 22 min & 30 min & 22 min & 34 min & 33 min \\ Shenzhen University & 28 min & 29 min & 35 min & 25 min & 33 min & 35 min \\ Daxin & 30 min & 29 min & 35 min & 30 min & 28 min & 33 min \\ Airport East & 19 min & 18 min & 26 min & 18 min & 23 min & 29 min \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Dynamic elapsed time thresholds of four stations under six scenarios. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Scenarios** & \multicolumn{2}{c}{**S1**} & \multicolumn{2}{c}{**S2**} & \multicolumn{2}{c}{**S3**} & \multicolumn{2}{c}{**S4**} & \multicolumn{2}{c}{**S5**} & \multicolumn{2}{c}{**S6**} \\ \cline{2-13}
**Stations** & **Static** & **Dynamic** & **Static** & **Dynamic** & **Static** & **Dynamic** & **Static** & **Dynamic** & **Static** & **Dynamic** & **Static** & **Dynamic** \\
**Model** & **Model** & **Model** & **Model** & **Model** & **Model** & **Model** & **Model** & **Model** & **Model** & **Model** & **Model** \\ \hline Guomoa & 927 & 899 & 217 & 210 & 341 & 341 & 182 & 174 & 142 & 143 & 393 & 406 \\ Shenzhen & 907 & 897 & 419 & 418 & 611 & 646 & 345 & 341 & 300 & 306 & 871 & 908 \\ University & Daxin & 1098 & 1098 & 917 & 917 & 642 & 666 & 420 & 420 & 409 & 406 & 806 & 827 \\ Airport East & 766 & 753 & 745 & 730 & 701 & 698 & 336 & 329 & 443 & 433 & 944 & 940 \\ \hline \hline \end{tabular}
\end{table}