An Integrated Spatial Framework for Seismic Risk Assessment of Critical Transport Corridors: A Multi-Criteria Decision Analysis for Istanbul’s D-100 Highway

Earthquakes disrupt transportation systems not only through structural damage but also through environmental conditions and functional dependencies. Since resource constraints require incremental resilience interventions, spatial risk prioritization is essential. This research proposes an integrated spatial framework to assess the seismic risk of critical transportation corridors and establish a basis for prioritization. The criterion hierarchy is structured into three main categories and thirteen sub-criteria, encompassing natural–geotechnical, structural–physical, and environmental–functional components of risk. Weights were derived using Fuzzy Analytic Hierarchy Process (FAHP) from a nine-person expert panel across three disciplines. Criterion scores were integrated within a Geographic Information System (GIS) environment to generate a spatial risk surface. The framework was applied to the Avcılar–Bakırköy section of the D-100 Highway in Istanbul. Sensitivity to expert composition was tested by comparing risk surfaces derived from discipline-specific weights. The findings indicate that seismic risk is too multidimensional to be reliably evaluated from a single disciplinary perspective, underscoring the imperative for a multidisciplinary approach. This interdisciplinary framework facilitates the identification of highway segments to be prioritized for detailed assessment. Ultimately, this work provides a holistic decision-support framework for corridor-based seismic risk assessment, whose workflow can be adapted to other corridors after local recalibration.