Optimization of Navigation Marking on Inland Waterways Using Multi-Criteria Analysis
This study develops a transparent and reproducible multi-criteria decision analysis (MCDA) framework for selecting the material and structural variant of floating navigation buoys on inland waterways. The decision problem was defined at the buoy-platform level and separated from external descriptive evidence on visual and radar performance. Three alternatives—galvanized steel, rotationally moulded polyethylene (PE), and mixed steel–PE—were assessed using the Weighted Sum Model (WSM) across eight non-overlapping technical, economic, and operational criteria. An eight-member purposive technical calibration panel screened the criteria, agreed their ordinal priority ranking, and validated the performance-class definitions—this panel was separate from a survey of 52 employees responsible for waterway maintenance. Technical performance classes were assigned from post-season condition assessments of 20 buoys per variant, whereas 36 repeated visual and radar observation series were treated as external descriptive evidence. In the baseline rank-sum model, steel buoys achieved 66.11 points, compared with 59.44 for PE and 54.44 for mixed buoys. Alternative rank-reciprocal and rank-order-centroid weight transformations retained steel as the highest-scoring alternative, while equal weights produced a tie between steel and PE (65.00 points each). One-factor sensitivity analysis showed that PE was preferred when the durability weight decreased from 22.22% to approximately 6.7% or when the corrosion-resistance weight increased from 19.44% to approximately 31%. Simultaneous perturbation of all weights retained steel as the highest-scoring alternative in 99.94% of simulations for ±30% perturbations and 95.17% for ±50%. The survey nevertheless showed greater practitioner preference for plastic or mixed solutions. The framework therefore provides an auditable, context-dependent decision process rather than a universal material recommendation and should be recalibrated and validated for other environmental and operational conditions.