Due to increasing traffic flows the extension of transport infrastructure with railroads and high-speed lines is an ongoing process worldwide. Ballastless track systems with concrete slabs are used more and more. Following the first trials in the 1970s and more than four decades of R&D work on the ballastless track, the level of development is such that it can be confirmed that the ballastless track is suitable for use as an alternative to ballasted track. This book makes a contribution to the state of the art of ballastless track by describing the basics for designing the ballastless track. Important advice is provided regarding the construction of ballastless tracks on earthworks and in tunnels. There is also a description of the technical history of the development of ballastless track on bridges and the ensuing findings for bridge design.