Longitudinal Forces and Deformations in Railway Tracks and Rail Expansion Joints on Bridges in Germany: A Review of Methods and Findings

Railway tracks on bridges are subject to longitudinal movements caused by temperature-induced stresses and train traction/braking forces, which generate track–bridge interaction and additional stresses in the rail. Rail expansion joints can compensate for these effects but are prone to malfunction and incur high maintenance costs. The technical regulations defining the basis for rail dimensioning may warrant re-evaluation, as they do not fully account for the current technical progress of superstructure systems. This paper reviews the state of the art in track–bridge interaction, focusing on rail longitudinal forces and deformations under thermal and traction/braking loads. The fatigue strength of railway rails, the action and dissipation of longitudinal forces, and track buckling are addressed first, followed by the mathematical principles governing rail longitudinal forces and deformations. Rail expansion joints and the key factors influencing track–bridge interaction are then discussed, along with field measurement approaches applied in related domains and the identified research gap. Finally, this gap is used to outline the need for future field investigations of the actual longitudinal forces and deformations in rail expansion joints on bridges, providing a basis for validating existing dimensioning verification methods for the rail.