A Conceptual Framework of Deterioration Factors for Sustainable Selection of Feasible Railway Track Solutions

Escalating track deterioration poses a significant challenge for infrastructure managers seeking to balance increasing capacity demands with long-term sustainability objectives. Although traffic loading is the primary driver of deterioration, existing deterioration models consider a wide range of additional factors whose representation varies across track forms. A comprehensive understanding of these factors is therefore necessary to support informed selection of railway track solutions. This study establishes a conceptual framework of deterioration factors for three railway track solutions: ballasted track, ballastless track, and combined track solutions (CTS). A systematic review of 30 deterioration models was conducted to identify deterioration factors and the mechanisms governing track degradation. Beyond synthesizing factors reported in existing deterioration models, the review identified five additional deterioration factors consistently associated with deterioration mechanisms in the broader railway engineering literature but not explicitly represented in the reviewed models. The review then evaluated the identified factors, grouped them by primary deterioration causes, and adapted them to reflect CTS-specific boundary conditions. The review revealed that existing deterioration models insufficiently address factors related to (i) properties of track subsystems and components, (ii) design characteristics of track forms, and (iii) design, location, and quantity of track transitions. Furthermore, deterioration-related parameters such as the elastic modulus of the track support and the amplitude and wavelength of differential settlement require specific consideration when assessing track form suitability within CTS. The resulting framework provides a structured conceptual representation of deterioration factors and their interrelationships, supporting future development of deterioration prediction models, life cycle cost assessments, and sustainability-oriented decision support methodologies for railway infrastructure.