The stability of the entire track and therefore the track geometry depends decisively on the load-bearing capacity of the formation protective layer (FPL). Problems arising in the foundation of the track increase the expenditure for track maintenance and shorten the service life of the track material. Enormous additional costs are the consequence.
Plasser American supplies extremely efficient machine systems for rehabilitation of line sections with substructure problems. These machines ride on the track and work in assembly-line mode to produce an optimum FPL. Using integrated ballast washing plants, crushing plants and mixers, large quantities of the old material can be reconditioned and used for the FPL, which saves considerable costs. Correct installation of geosynthetics helps to achieve an excellent initial quality of the track, thus substantially raising the quality reserve.
Poor drainage of water, an outdated layer structure or local features in the composition of the subsoil materials can reduce the load-bearing capacity of the subsoil decisively. Consequently, this reduces the stability of the entire track system and costs rise for maintenance of the sections of track concerned. At the same time damage occurs in the track materials.
A decisive factor for long life of the track system is efficient drainage of water from the track. Beyond that a correct layer structure of the subsoil and the ballast bed must be guaranteed, allowing for local events such as fixed structures, bridges, cable ducts and so on.
Formation rehabilitation machines perform all the necessary tasks in one operation without disrupting rail traffic on the adjacent track. A formation protective layer (FPL) is installed in order to raise the load-bearing capacity of the subsoil effectively und sustainably. Good results are obtained by installing an FPL made of a sand-gravel mix that is inserted under the ballast bed and consolidated. Geosynthetics can also be installed in the same working pass.