## 4 Results and Discussion
### GMM Clustering Based on Stay Time
#### 4.2.2 Analysis of Weekday and Weekend Ridership  
As shown in Figure 11, the clustering results distinguish the peak distribution of intercity ridership in terms of stay time and effectively identify travel groups under different travel patterns. A comparative analysis of the differences between the intercity ridership \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Type** & **Weight** & **Mean** & **Standard Deviation** \\ \hline Gaussian distribution 1 & 0.7912 & 4.30 & 2.75 \\ Gaussian distribution 2 & 0.2088 & 23.47 & 5.25 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: The estimated parameters of each stay-time clustering component. Figure 10: Stay-time distribution of intercity ridership. groups on weekends and weekdays shows that, on the whole, the daily intercity ridership on weekends is greater than that on weekdays. On weekends, the short-stay-time group accounts for 76.4% and the long-stay-time group accounts for 23.6%. On weekdays, the short-stay-time group accounts for 90.8% and the long-stay-time group accounts for 9.2%. It can be seen that whether it is on weekends or weekdays, the stay pattern of intercity ridership is mainly round trip on the same day, which is easy to understand. Especially for weekdays, the main travel purpose of the short-stay-time group is cross-city commuting (work, school, etc.) or service (medical, business, etc.). In addition, the proportion of overnight ridership on weekends is significantly higher than that on weekdays, which is related to the fact that more tourists on weekends are traveling, and their overnight demand is higher. To further investigate the travel patterns of intercity ridership, the short-stay-time group and the long-stay-time group on weekends and weekdays were compared based on travel purposes. For intercity trips from Xiangtan to Changsha, the top 20 alighting ridership stations in Changsha are shown in Figures 12 and 13, respectively. The following can be found:On weekends, the main travel destinations of the short-stay-time group and the long-stay-time group are similar, and their main travel destinations both are Wuyi Square, Yanghu Wetland, and Huangxing Square, respectively, reflecting that their main travel purpose is leisure. That is, the intercity ridership groups with tourism as their travel purpose on weekends have different stay patterns, but their main travel destinations are similar. However, for residential office-intensive areas, the long-stay-time group obviously has a higher stay time than the short-stay-time group, such as Yangguang and Xingsha. The travel demand of the ridership is more about residential demand or service demand, rather than leisure, so its overnight demand is significantly higher than the round trip on the same day. On weekdays, there are large differences in the distribution of main travel destinations between the short-stay-time group and the long-stay-time group. For the short-stay-time group, the main travel destinations are Yanghu Wetland (11.7%), Wuyi Square (10.0%), and Yanghu ECO Town (4.6%). The Yanghu area consists mainly of many large-scale shopping centers (IKEA, Livat, etc. ), scenic spots (park, museum, etc. ), office buildings, residential areas, etc. And Wuyi Square and Huangxing Square form the business center of Changsha, featuring huge jobs, tourism, entertainment, shopping facilities, etc. The result reflects that the main travel purposes of round trips on the same day are work and leisure. For the long-stay-time group, the main travel destinations are Yanghu Wetland (6.2%), Houjiatang (4.9%), and Central South University (3.7%), which reflect the main commuting demand for overnight stay on weekdays (work, school, etc.). In addition, the proportion of intercity ridership groups traveling to hospitals (Xiangya Hospital, the Second Xiangya Hospital) on weekdays is significantly higher than on weekends. It can be seen that the travel purpose of intercity ridership on weekdays is more diversified, including leisure, commuting (work, school, etc.