A Comparative Analysis of the Dynamic Performance of Ballasted and Ballastless Track Systems for High-Speed Turnouts

Railway infrastructure plays a fundamental role in enabling the daily movement of people and goods. In a context characterised by higher dynamic loads, speeds, and traffic demand, it is essential to continuously ensure safety and operability of the network and its subcomponents. Among these, turnouts are particularly critical systems due to their geometric complexity, the high maintenance costs involved and their function. Because of the geometry of wheel–rail contact and the abrupt variations of track flexibility, severe impact loads are generated during train crossing. These loads can significantly damage the turnout and accelerate the degradation of the supporting track substructure, compromising the safety functioning of the system. In this work, a preliminary comparative analysis is conducted considering, respectively, turnouts laid on conventional ballasted and ballastless layers. To this end, a detailed finite element model of a high-speed movable-point turnout has been developed, accounting for the variability of rail profile along the longitudinal direction. The dynamic interaction between the trainset, modelled through a multi-body approach, and the turnout structure is simulated using a non-commercial software developed inside the Department of Mechanical Engineering at Politecnico di Milano. Train-track coupling is realised through wheel-rail contact forces, defined using a multi-Hertzian approach that can reproduce the formation of multiple contacts between each wheel and the different rails. The two track options are compared in terms of track accelerations as well as dynamic forces transmitted to the ground. For the turnout sections considered and under the simulation parameters adopted, sleeper midspan acceleration levels were found to be higher for the slab track configuration. Nevertheless, this solution provides a more uniform distribution of the forces transmitted to the ground, thereby reducing their peak values.