Today’s social infrastructure, e.g., transportation, medical services, energy supply and distribution, may become temporarily unable to provide functions due to the damage to buildings or excessive congestion resulting from threats, such as natural disasters, rising sea levels, pandemics. Maritime-based responses, typified by hospital ships, are drawing attention as a method to mitigate these effects. However, while designing emergency infrastructure, it is necessary to consider not only the value of these systems in emergencies but also during normal times. This study adopts the systems approach, a set of methods to conduct decision-making when complex stakeholders’ relationships are involved. We focus on medical functions and propose a conceptual design for a flexible hospital ship with dynamic capability during emergencies as well as normal times. Specifically, we examine the optimal combination of ship type, size, navigation range during normal times, operations during emergencies, and contract approaches. Quantitative evaluation of utility during emergencies and economic efficiency are considered in tradeoff. In addition to the conventional cost-based study, we examined benefit–cost through ship sharing, in which ships are leased to the private sector as merchant vessels during normal times to generate revenue.

当今的社会基础设施，如交通、医疗服务、能源供应和分配等，可能会因自然灾害、海平面上升、流行病等威胁造成建筑物损坏或过度拥堵而暂时无法提供功能。以医院船为代表的海上应对措施作为减轻这些影响的方法正在引起人们的关注。然而，在设计应急基础设施时，不仅要考虑这些系统在紧急情况下的价值，还要考虑正常情况下的价值。本研究采用系统方法，即涉及复杂的利益相关者关系时进行决策的一套方法。我们专注于医疗功能，并提出了一种灵活的医院船概念设计，该医院船在紧急情况和正常情况下都具有动态能力。具体来说，我们研究了船舶类型、尺寸、正常情况下的航行范围、紧急情况下的操作以及合同方法的最佳组合。紧急情况下的效用和经济效率的定量评估是在权衡中考虑的。除了传统的基于成本的研究之外，我们还通过船舶共享研究了收益-成本，其中船舶在正常情况下作为商船出租给私营部门以产生收入。