Type of sleeper on main tracks

Kilometres of main tracks by type of sleepers since 2006.The rails are generally fixed on raag pieces(sleepers, longitudinal beams, timber pieces) and exceptionally on a full concrete slab.The sleepers have a dual purpose: to hold the two rails in place and thus achieve and maintain the imposed track gauge; to support the rails and transfer the loads from the trains evenly onto the ballast.On the main tracks, you will find the following types of sleepers :Wood : in oak or azobob Concrete : two generation, old and newMetal