Effect of track type replacement on dynamic performance of short-span railway bridges of conventional lines

It is generally acknowledged that dynamic effects might be critical for the performance of rail-way viaducts and, thus, design codes have imposed serviceability checks based on various pa-rameters e.g. maximum accelerations and deformations. The track typology plays a significant role on the dynamic response of railway viaducts since it affects relevant dynamic properties (mass, inertia, or the way the traffic loads are distributed from the rails to the girder). Therefore, it is of interest to understand the influence of the track type on viaducts’ dynamic behavior. In Spain, a new ballastless track system based on precast, prestressed concrete slabs has been in-troduced in high-speed railway viaducts for the last years and specific dynamic studies have verified its appropriate behavior. Other interesting applications of such system is the rapid track renovation in existing bridges of conventional lines. In order to understand the influence of the track typology, the present contribution shows a dynamic comparative study of ballasted and ballastless track types of short-span bridges for conventional lines in Spain. Numerical models including track-bridge interaction have been completed for speeds smaller than 220 km/h for relevant train models. The conclusions show that the performance of precast ballast-less track system is adequate and provides an efficient solution for track renovations.