Track Vertical Stiffness –Value, Measurement Methods, Effective Parameters and Challenges: A review

• A comprehensive literature review of the track vertical stiffness and rail support modulus. • Comprehensive classification of track vertical stiffness measuring methods, concepts, and assumptions. • Scrutinizing the effective parameters, modification methods, and practical approaches. The track structural performance is ensured by understanding the track vertical response to the applied loads and bearing and transmitting these loads with minor permanent deformation. There is a global trend toward higher axle loads and train speeds, particularly on heavy haul lines. Therefore, it has become critical to examine the track's structural state promptly and correctly. As one of the most influential factors for recognizing track vertical behavior, vertical stiffness has been a concern in ballasted railway track design, analysis, defect detection, and maintenance procedures. So far, extensive research has been done on the concepts, measuring methods, quantifying, and influential parameters on track vertical stiffness. This paper comprehensively reviews the vertical stiffness measurement methods, values, and effective ballasted track parameters and their contribution to railway track condition monitoring.