This study explores how storm surge barriers, essential for protecting flood-prone urban regions like the Texas Gulf Coast, can be designed to remain reliable and adaptable over their 100 year lifespans despite unpredictable environmental and socio-economic changes. Traditional flood defenses like dikes are often unfeasible in dense cities, prompting the adoption of movable storm surge barriers. However, fewer than fifty such barriers exist worldwide, and operational knowledge remains fragmented. Once built, barriers must maintain near-perfect reliability despite unpredictable factors such as sea level rise, changing vessel sizes, and institutional shifts, conditions that standard design practices often fail to accommodate.

Focusing on the proposed Bolivar Roads Gate System, the research integrates operational and maintenance needs into early design and planning. It applies the Flexibility in Engineering Design method to identify and evaluate how external drivers, like relative sea level rise and economic development (particularly increased vessel drafts), affect long-term barrier performance. The study maps dependencies between critical system drivers and barrier components, identifying the sill as the most risk-sensitive and costly to modify. As a result, it proposes an innovative, adaptable sill design: a two-stage structure that can be upgraded in the future to accommodate deeper vessel drafts, allowing the barrier to “change” rather than fail under unanticipated pressures.

The study also identifies the importance of designing for maintainability. Barrier components have varying lifespans, electrical (8–15 years), movable (50–100 years), and fixed (100 years), which demand different maintenance intervals. To address this, the research advocates for a maintainability-first design strategy, such as placing short-lived components in easily accessible locations. Maintenance should follow a state-based policy, combining preventive, corrective, and failure-based actions depending on the component’s role and risk level.

From a governance perspective, the study highlights the need for public clients to act as system integrators, balancing in-house oversight with selective outsourcing. The delivery of such complex infrastructure requires differentiated strategies across phases: detailed design should remain tightly managed in-house, while construction and certain maintenance tasks may be outsourced. Operational control, due to high reliability demands, should stay within the public domain. The governance of adaptable components, like the sill, must also remain with public authorities to ensure activation aligns with policy shifts.

Ultimately, the research proposes a bimodal strategy for barrier management. Mode 1 focuses on maintainability and predictable reliability through conventional design and maintenance practices. Mode 2 embraces uncertainty, embedding flexibility into components to adapt over time. This approach enables barriers to function as dynamic, living systems, built to endure, but also to evolve. By embedding adaptability in the most permanent elements and pairing it with tailored maintenance strategies, public agencies can maintain flood protection, performance, and accountability in the face of long-term uncertainty.