A transportation network is a critical lifeline for a community, essential to the functioning of society and the viability of the economy. The wellbeing of the community’s members depends on their mobility, ability to move goods, and access to services. Having a resilient transportation infrastructure system that performs well under multiple hazard situations is critical to a community. A transportation system is a complex, multi-modal system consisting, among other modes, of rail, highway, air, and maritime networks, and ports or other intermodal connections which link such networks. Moreover, transportation networks are inherently interconnected with other critical lifelines, including power, telecommunications, water, sanitation, and building infastructure networks, which are themselves complex systems. This work develops a deeper understanding of the effects of interactions between critical infrastructure lifelines (including water, wastewater, power, natural gas, communications and cyber) and transportation systems. It further investigates the role of these interdependencies in transportation system resilience, and develops resilience quantification tools that account for the impact that arises from these interdependencies on resilience level.