Identifying Critical Links in Degradable Road Networks Using a Traffic Demand-Based Indicator

The primary traffic-based indicators for identifying critical links account for travel time, transportation efficiency, and traffic demand. These indicators are seldom applied to scenarios in which link capacity degradation occurs across the entire network. In addition, the commonly used traffic demand-based indicator, known as unsatisfied demand, can only work when there are disconnected origin–destination (OD) pairs in the network. In this context, this study incorporates the concept of a degradable road network to represent such scenarios and introduces a new network-wide traffic demand-based indicator, defined as late arrival demand (LAD), to identify critical links. Specifically, we built a late arrival rate (LAR)-based user equilibrium (UE) model to capture travel behavior and estimate the LAD in degradable road networks. Then, LAD and four other indicators were introduced to identify critical links in the framework of the LAR-based UE model. Finally, the Nguyen–Dupuis and Sioux Falls networks were employed for numerical experiments. The results, under various levels of traffic demand and degradation, demonstrate that LAD is a flexible and effective network-wide traffic demand-based indicator. This new approach provides insights that can help managers assess link criticality in degradable road networks from the perspective of traffic demand.