Initially intended as national projects connecting the larger cities within a country, the high speed routes were linked to each other to form a network and were inter-connected to the conventional railway network, thus enabling time-savings to be made on the high speed lines.

The possibility of covering distances of over 100 km in just few hours has enabled high speed rail to compete on longer distances.

Thus the idea was born of having international corridors or an inter-state system connecting routes between different countries such as France and Spain, the UK and continental Europe, Zurich and Milan, as well as the Northeast Californian corridor.