(2) Betweenness centralityBetweenne

(2) Betweenness centralityBetweenness centrality is a way of detecting the amount of influence a node or edge has over the flow of information in a graph. It is often used to find nodes or edges that serve as a bridge from one part of a graph to another (Wang et al., 2019). Betweenness is considered as an important tool in safety management. In an accident network, if the bridge is broken, all the OD pairs (Wang et al. 2015) of sub-events cannot be accessed. he betweenness centrality of node or edge is calculated by the ratio of the number of shortest paths passing through this node or edge to all the shortest paths between all OD pairs in SEIN. A path means how many nodes an incident goes through in which the shortest path refers to the least passed nodes. The value of the betweenness is between 0 to 1. The higher the betweenness, the more importance of the sub-events or the edges between sub-events in SEIN. The top ten betweenness for each sub-event and each edge of two neighbor sub-events is presented in Table 3.