A system for loading, unloading and rail transportation of road-hauled semi-trailers, having multiple wagons (1) constituting a railway train, with each of them incorporating at least one pivotable turntable (14) for accommodating a semi-trailer via its wheel assembly. The system also comprises a detachable hitch mounting (9) that can be gripped by a handling machine which carries the detachable mounting and assembles it, after adjustment on the semi-trailer's pivoting turntable. The hitch mounting is assembled on an accommodating platform (8) that is secured immobile to the wagon chassis (2) and independently of the pivoting turntable, in order to support the front of the semi-trailer during rail transportation. This invention is of interest to rail carriers and railway transport equipment manufacturers.