Civil infrastructure, particularly railway bridges, experiences continuous degradation from operational loads, environmental conditions, and material ageing, making their monitoring crucial for safety and economic sus-tainability. Structural Health Monitoring (SHM) represents a paradigm shift from periodic visual inspections to continuous, data-driven assessment of structural integrity. At the heart of SHM lies the principle that dam-age or deterioration manifests as changes in a structure's dynamic properties, particularly its natural fre-quencies (eigenfrequencies), mode shapes, and damping ratios. These modal parameters serve as the struc-ture's „fingerprint,“ where even subtle shifts can indicate developing problems long before visible damage appears. Among various monitoring approaches, drive-by monitoring, using sensors on passing vehicles ra-ther than fixed instrumentation on the structure, offers a compelling solution that transforms regular railway traffic into a continuous inspection fleet, eliminating the need for costly permanent sensor installations on thousands of bridges across the network.