Transition zones between bridges, tunnels, artificial and earth structures, including transitions between ballast and non–ballast permanent way (slab track), are a part of the railway track structure where the abrupt change in the rigidity of the track structure and track settlement occurs between individual transverse profiles, as a result of the change in the structural elements and the foundation. Variation in the rigidity of the rail structure is the basic parameter influencing the generation of new impulse mechanisms during interaction between the vehicle and the structure. This causes additional dynamic loads, resulting in further degradation of the track structure and indirect decrease in the level of safety and comfort of railway traffic. Due to foregoing, the transition zones are defined as exceptionally problematic parts on the railway track. In order to limit additional and frequent costs of rehabilitation of these track parts, the degradation mechanisms are analyzed within EU funded research project (SMART RAIL), with the aim to find a high–quality, economically and environmentally acceptable solution for existing older railways.
This paper presents the mechanisms influencing the degradation of tracks in the transition zones, as well as structural measures presently known and used for rehabilitation of existing railways.

transition zones, degradation of the railway track, structural measures