Identification and Quantification of Node Criticality through EWM\u2013TOPSIS: A Study of Hong Kong\u2019s MTR System

Yifan Zhang,S Thomas Ng

doi:10.1007/s40864-021-00155-6

Yifan Zhang, S Thomas Ng

Open Access

https://doi.org/10.1007/s40864-021-00155-6

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Abstract

Public transport networks (PTNs) are critical in populated and rapidly densifying cities such as Hong Kong, Beijing, Shanghai, Mumbai, and Tokyo. Public transportation plays an indispensable role in urban resilience with an integrated, complex, and dynamically changeable network structure. Consequently, identifying and quantifying node criticality in complex PTNs is of great practical significance to improve network robustness from damage. Despite the proposition of various node criticality criteria to address this problem, few succeeded in more comprehensive aspects. Therefore, this paper presents an efficient and thorough ranking method, that is, entropy weight method (EWM)–technology for order preference by similarity to an ideal solution (TOPSIS), named EWM–TOPSIS, to evaluate node criticality by taking into account various node features in complex networks. Then we demonstrate it on the Mass Transit Railway (MTR) in Hong Kong by removing and recovering the top k critical nodes in descending order to compare the effectiveness of degree centrality (DC), betweenness centrality (BC), closeness centrality (CC), and the proposed EWM–TOPSIS method. Four evaluation indicators, that is, the frequency of nodes with the same ranking (F), the global network efficiency (E), the size of the largest connected component (LCC), and the average path length (APL), are computed to compare the performance of the four methods and measure network robustness under different designed attack and recovery strategies. The results demonstrate that the EWM–TOPSIS method has more obvious advantages than the others, especially in the early stage.

Highlights

Public transport networks (PTNs), including buses, trolleybuses, trams or light rail, rapid transit, and ferries, are the backbone and central pillars for urbanization
This paper presents an efficient and thorough ranking method, that is, entropy weight method (EWM)–technology for order preference by similarity to an ideal solution (TOPSIS), named EWM–TOPSIS, to evaluate node criticality by taking into account various node features in complex networks. We demonstrate it on the Mass Transit Railway (MTR) in Hong Kong by removing and recovering the top k critical nodes in descending order to compare the effectiveness of degree centrality (DC), betweenness centrality (BC), closeness centrality (CC), and the proposed EWM–TOPSIS method
Nodes ranked by DC are divided into four categories according to the degree’s value; for example, the top eight nodes share the same ranking with four adjacent nodes

Summary

Introduction

Public transport networks (PTNs), including buses, trolleybuses, trams or light rail, rapid transit (i.e., metro, subway, underground), and ferries, are the backbone and central pillars for urbanization. As a result, identifying vulnerabilities of each component of PTNs has recently generated considerable research interest in the impacts of disruptive events. Critical nodes can affect the structure and function of complex networks more significantly than the others [1]. It reflects its control over structural connectivity and contributions to the functional operability of the system. Identifying the critical nodes is of considerable significance in analyzing the vulnerability and fragility of a tiny fraction of critical nodes against disruptive events [2,3,4,5].

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