## 5 Analysis of Examples
### Cluster Grading and Effectiveness Analysis of the Status Values of Traffic Interruptions
#### 5.2.2 Validity Analysis
Disadvantages: Although this level of clustering provides more detailed information, it may still have limitations. As the number of clusters increases, the similarities between some events may become diluted, possibly categorizing very similar events into different clusters and slightly increasing the complexity of the analysis. 3. Higher number of clusters: The interruption classification can be further subdivided to show more specific features. However, when there are too many levels, the boundaries between different categories may become blurred, resulting in similar samples being assigned to different categories, reducing the validity of the clustering. For example, some events were categorized into level-1 and level-5 when n_cluster = 5. Advantages: More clusters can help identify specific traffic interruption patterns and reveal more nuanced characteristics of the interruptions. For example, by using a large number of clusters, very rare but highly impactful events can be identified, aiding in the formulation of more precise recovery plans. Disadvantages: However, with too many clusters, the classifications become overly detailed, leading to blurred boundaries between categories. This can cause very similar events to be inconsistently grouped into different categories, which could confuse decision-makers and make management more complex. By analyzing the different numbers of clusters, we can observe that the gradual decrease in the PE values except for the two-level classification indicates that the validity of the clustering results has been improved. Specifically, the PE value is 0.043 for the two-level classification and 0.057 for the four-level classification. Although the two-level classification is more valid than the four-level classification in terms of PE value, we recommend the four-level classification scheme rather than the two-level scheme from a practical application point of view. The four-level classification scheme not only has a lower value of PE, but also ensures an accurate classification of the value of the traffic interruption status, contributing to a more comprehensive understanding of the severity and impact of the different highways to Tibet in the face of traffic interruptions. In the four-level classification, it can be found that the interruptions of the Sichuan-Tibet Highway (events 128-186) and Xinjiang-Tibet Highway (events 207-642) belong to level-3 and level-4 serious interruptions more than the other two highways, and most of the high-level interruptions of the Qinghai-Tibet Highway (events 1-127) are level-2 ordinary interruptions. The Yunnan-Tibet Highway, due to the limited data and its classification primarily in level-1, is not analyzed in detail in this paper. The Sichuan-Tibet Highway was constructed in the 1950s, when lower construction standards and complex geological and climatic conditions made the route more prone to serious traffic disruptions. The Xinjiang-Tibet Highway passes through the world-famous Kunlun Mountains and the Himalayas, with an average altitude of more than 4500 m, making it the world's highest and most dangerous plateau highway. It is also prone to serious traffic interruptions at levels-3 and level-4. The Qinghai-Tibet Corridor, on the other hand, is relatively less severe overall, despite the fact that there have been disruptions. These findings are important guidance for road management to develop targeted maintenance and emergency response measures. In particular, the Sichuan-Tibet Highway, with a lower construction standard and complex geo-climatic conditions, requires more attention and resource investment to improve its resilience and reduce the impact of traffic interruptions.