Increasing line load from higher axle loads and train frequencies takes the present infrastructure to its limits. In addition to using higher-quality superstructure materials, the carrying capacity and drainage of the subgrade are central parameters for economically efficient operation of the railway infrastructure. If the track bed cannot drain properly, the underground will give and become volatile. Only exponential massive use of track tamping machines and expensive regravelling permits continuing operation of the lines. It is also only a temporary solution before the subgrade has to be rehabilitated to recover its draining properties.

This may be done conventionally, i. e. by removal of the track panels, excavation of the subgrade creating a new track bed and subsequent reconstruction of the track. There is another, rail-bound, option as well. While the new subgrade protection layer is destroyed again by trucks and other construction-site vehicles in conven­tional sub­grade rehabilitation, rail-bound work will lead to perfect quality.