Towards Unifying Resilience and Sustainability for Transportation Infrastructure Systems: Conceptual Framework, Critical Indicators, and Research Needs

Sustainability aspects of transportation infrastructure systems primarily focus on system performance based on environmental, social, and economic impacts. In contrast, resilience aspects demonstrate the ability to withstand external shocks i.e. robustness as well as to recover from the loss of functionality due to such disruptions i.e. rapidity. Therefore, sustainability and resilience are two key aspects which should be given adequate attention during the planning, design, construction, operations, and maintenance phases of any civil infrastructure system. As both concepts are equally important to sustain an infrastructure for a longer duration, their concurrent assessments within a unified framework are highly desirable. While there has been a recent focus towards solving this dilemma, review of existing studies revealed the lack of such unifying frameworks that can quantify sustainability and resilience indicators to simultaneously assess system performance. Moreover, a single decision or performance indicator could reinforce one and undermine another. As such, this study proposed a forward-looking unification framework, where the sustainability and resilience of transportation infrastructure systems can be analyzed simultaneously. In this regard, the proposed unifying framework is explained using seven critical indicators including emission, speed, temperature, energy consumption, delay, mobility, and accessibility. This study also investigates the interdependencies, relationships, and tradeoffs between sustainability and resilience based on these indices. While some indices would help the system to attain both at the same time, they are compromised in some cases. Finally, the study identifies immediate research needs as well as the ones in the long-term.