Integrating equity and efficiency into urban logistics resilience under emergency lockdowns

The urban logistics system serves an essential role in providing daily necessities for residents but is vulnerable to resource shortages in disasters. For instance, cluster infections and access restrictions caused by public health emergencies like COVID-19 pose a severe challenge to the resilient operations of urban logistics systems. Especially, the restriction level and the labor shortage always vary a lot on a citywide basis, resulting in a dilemma in handling distributional equity and delivery efficiency. Motivated by this issue, this paper studies the resilience assessment method and enhancement strategy for urban logistics systems under emergency lockdowns with integrated consideration of equity and efficiency. The resilience-oriented capacity reallocation models are developed for quick-response strategies in the case of two disruption types, i.e., closure of distribution centers and capacity degradation of delivery routes. Numerical studies of a real-world case in Shanghai are conducted to illustrate the feasibility and effectiveness of our methods under different disruption levels. The comparison of reallocation schemes with respect to different weights of equity and efficiency is also performed to discuss their impacts on resilience. The results indicate the importance of considering equity in logistics distribution under large-scale disruptions. If distributional equity is highly valued, the service capability can retain up to 74 % of the original level despite half of the distribution centers being shut down. In addition, different concerns on equity and efficiency can lead to variations in system resilience for the same disruption scenario, but the capacity reallocation schemes consistently align with the aim of resilience enhancement. Finally, several managerial insights are provided for decision-makers on urban logistics planning and intelligent disaster management during emergencies.