Alysha Helmrich

Infrastructure systems are increasingly exposed to uncertainty, complexity, and rapid change. Natural hazards, accelerating technological development, and growing interdependencies among infrastructure sectors have made infrastructure failures more difficult to anticipate, model, and manage. While individual infrastructure systems are often well understood, their interactions, particularly the cascading failures and nonlinear dynamics that emerge during disruptions, remain poorly captured in practice. Many existing assessment approaches continue to treat infrastructures as largely independent systems, limiting their ability to support decision-making in environments characterized by emergence, surprise, and compounding risk. This paper addresses this gap by identifying, cataloging, and evaluating infrastructure interdependency assessment tools scoped to three sectors: energy, water, and transport. A structured, multi-stage process was used to compile a comprehensive inventory from peer-reviewed and gray literature. Tools were classified and evaluated using a dual framework that combines quantitative scoring of technical dimensions and qualitative assessment of categorical characteristics. The analysis identifies 24 tools within scope, of which only seven explicitly support system-of-systems interdependency assessment for the identified infrastructures. Results reveal an uneven tool landscape: dominance of sector-specific tools, strong emphasis on physical interdependencies, and limited integration of broader interdependency classifications. A fundamental tradeoff emerges between model complexity and practical usability, with no single tool capturing the full breadth of interdependency behavior. By providing a structured comparison and classification of available tools, this study offers guidance on tool selection and highlights key gaps in current modeling approaches, contributing to the advancement of infrastructure resilience assessment in complex, interdependent systems.

Infrastructure systems have typically been designed under assumptions of stability, yet the conditions cities face are increasingly uncertain and difficult to predict. This perspective argues that to respond effectively to the uncertainty brought about by changing conditions, infrastructure must shift from rigid to flexible systems. We conceptualize flexibility as the capacity of infrastructure to render human-centered affordances (i.e. realized infrastructure services that enable human capabilities) across six levers: spatial, quantity, temporal, configurable, functional, and institutional. We explore these levers in the context of urban shrinkage and transportation systems, and we discuss their implications for infrastructure management, trade-offs and risks, equity, and education. This perspective offers a structured lens for exploring where, how, and for whom flexibility should be embedded in infrastructure systems facing uncertainty, with implications that extend beyond transportation to water, energy, and other critical infrastructures.

To account for increasing complexity and uncertainty in environmental, social, and technological systems, organizations that manage risk and vulnerability while maintaining large physical asset or infrastructure projects must identify, inventory, and anticipate trade-offs across multiple drivers of change. This article describes an integrated and inclusive process to develop a capabilities-based planning (CBP) framework to inform decision-making for future investments, centering hazard risk reduction and operational resilience. The proposed CBP framework demonstrates an approach to addressing context-specific complexity and uncertainty in decision-making by assessing short and long-term risk within a defined analytic focus. A case study of application is provided, examining the impacts of climate, resource, population, urbanization, and technology drivers on foreign assets for the U.S. Department of State Bureau of Overseas Buildings Operations in Kolkata, India. The process broadly applies to organizations with projects of physical assets and critical infrastructure, which balance tensions in decision-making across multiple objectives in diverse contexts.

Critical Infrastructure Systems (CISs) provide essential services for nation-wide security, economy, and social well-being, and these systems are becoming increasingly interdependent to maintain those services. Recent and diverse disturbances worldwide have highlighted that interdependencies within CISs may increase the potential for cascading failures, amplifying the impacts of both large and small-scale disturbances into events of catastrophic proportions. The methodology involved conducting a literature search through scholarly databases and using a snowball approach to identify 12 relevant papers on infrastructure interdependencies. Thematic analysis was then applied to classify 50 interdependencies, which were synthesized into a unified classification system mapped to a foundational framework. The direct citation network visualization tool, Kumu, illustrated citation patterns and guided the analysis. Identifying and classifying various interdependencies, understanding their relationships, and assessing their role in CISs are crucial steps to prevent, mitigate, or manage unfavorable consequences and enhance system resilience. In this article, classifications of infrastructure interdependencies were compiled and identified and a unified classification was described. To support the resilience of CISs in periods of stability and instability, infrastructure managers not only need consistent terminology but a shared understanding of interdependencies to ensure said interdependencies within and across CISs are appropriately accounted for throughout the life cycle of infrastructure, from early planning stages to management—reactive or proactive—for disturbances. These are critical steps toward understanding how CISs operate in concert so infrastructure managers may sense and anticipate potential disruptions, manage the impacts and consequences, and adapt to changing future conditions.

Extreme weather-related events are showing how infrastructure disruptions in hinterlands can affect cities. This paper explores the risks to city infrastructure services including transportation, electricity, communication, fuel supply, water distribution, stormwater drainage, and food supply from hinterland hazards of fire, precipitation, post-fire debris flow, smoke, and flooding. There is a large and growing body of research that describes the vulnerabilities of infrastructures to climate hazards, yet this work has not systematically acknowledged the relationships and cross-governance challenges of protecting cities from remote disruptions. An evidence base is developed through a structured literature review that identifies city infrastructure vulnerabilities to hinterland hazards. Findings highlight diverse pathways from the initial hazard to the final impact on an infrastructure, demonstrating that impacts to hinterland infrastructure assets from hazards can cascade to city infrastructure. Beyond the value of describing the impact of hinterland hazards on urban infrastructure, the identified pathways can assist in informing cross-governance mitigation strategies. It may be the case that to protect cities, local governments invest in mitigating hazards in their hinterlands and supply chains.

Infrastructure systems have legacies that continue to define their priorities, goals, flexibility, and ability to make sense of their environments. These legacies may or may not align with future needs, but regardless of alignment, they may restrict viable pathways forward. Infrastructure ‘lock-in’ has not been sufficiently confronted in infrastructure systems. Lock-in can loosely be interpreted as internal and external pressures that constrain a system, and it encourages self-reinforcing feedback where the system becomes resistant to change. By acknowledging and recognizing that lock-in exists at small and large scales, perpetuated by individuals, organizations, and institutions, infrastructure managers can critically reflect upon biases, assumptions, and decision-making approaches. This article describes six distinct domains of lock-in: technological, social, economic, individual, institutional, and epistemic. Following this description, strategies for unlocking lock-in, broadly and by domain, are explored before being contextualized to infrastructure systems. Ultimately, infrastructure managers must make a decision between a locked in and faltering but familiar system or a changing and responsive but unfamiliar system, where both are, inevitably, accepting higher levels of risk than typically accustomed.

Complex adaptive systems – such as critical infrastructures (CI) – are defined by their vast, multi-level interactions and emergent behaviors, but this elaborate web of interactions often conceals relationships. For instance, CI is often reduced to technological components, ignoring that social and ecological components are also embedded, leading to unintentional consequences from disturbance events. Analysis of CI as social-ecological-technological systems (SETS) can support integrated decision-making and increase infrastructure’s capacity for resilience to climate change. We assess the impacts of an extreme precipitation event in Phoenix, AZ to identify pathways of disruption and feedback loops across SETS as presented in an illustrative causal loop diagram, developed through semi-structured interviews with researchers and practitioners and cross-validated with a literature review. The causal loop diagram consists of 19 components resulting in hundreds of feedback loops and cascading failures, with surface runoff, infiltration, and water bodies as well as power, water, and transportation infrastructures appearing to have critical roles in maintaining system services. We found that pathways of disruptions highlight potential weak spots within the system that could benefit from climate adaptation, and feedback loops may serve as potential tools to divert failure at the root cause. This method of convergence research shows potential as a useful tool to illustrate a broader perspective of urban systems and address the increasing complexity and uncertainty of the Anthropocene.

The 2022 Southwest Airlines Scheduling Crisis, resulting in approximately 15 000 flight cancellations, demonstrates the challenges of structuring infrastructure systems and their knowledge-making processes for increasingly disruptive conditions. While the point-to-point configuration was the focus of immediate assessments of the failure, it became rapidly evident that the crew-assignment software was unable to operate effectively due to the scale of disruption. The airline failed to recognize environmental shifts associated with internal and external complexity, leaving operations vulnerable to a known potential risk: computer and telecommunications failures due to an extreme weather event resulting in knowledge systems failures. The cascading failures of the crisis emphasize the necessity to invest in adaptive capacity prior to catastrophic events and provide a lesson to other infrastructure managers pursuing resilience in the face of increasingly uncertain environments.

As infrastructure confront rapidly changing environments, there is an immediate need to provide the flexibility to pivot resources and how infrastructures are prioritized. Yet infrastructures are often categorized based on static criticality framings. We describe dynamic criticality as the flexibility to reprioritize infrastructure resources during disturbances. We find that the most important prerequisite for dynamic criticality is organizational adaptive capacity characterized by flexible goals, structures, sensemaking, and strategies. Dynamic capabilities are increasingly important in the Anthropocene, where accelerating conditions, uncertainty, and growing complexity are challenging infrastructures. We review sectors that deployed dynamic management approaches amidst changing disturbances: leadership and organizational change, defense, medicine, manufacturing, and disaster response. We use an inductive thematic analysis to identify key themes and competencies and analyze capabilities that describe dynamic criticality. These competencies drive adaptive capacity and open up the flexibility to pivot what is deemed critical, depending on the particulars of the hazard. We map these competencies to infrastructure systems and describe how infrastructure organizations may build adaptive capacity toward flexible priorities.

Climate-related disruptions expose the obduracy of existing urban systems built to deal with conditions of the past without the needed flexibilit |