The project is strongly supported by the European Union and it is based on four international Treaties between Italy and France stipulated in 1996, 2001, 2012 and 2015 (modified in 2016). Between the end of 2016 and the beginning of 2017, the Italian and French Parliaments have ratified the agreement that starts the definitive work.

The current configuration of the cross-border section in Italy is the result of participatory planning with the involvement of local authorities. In Italy in particular, the final route, one that is radically different from the original project, was agreed on thanks to the work of the Observatory on the Turin-Lyon line chaired by the Government Commissioner, at the end of 205 work sessions and 300 audiences with technicians and experts. The definitive route of the Turin-Lyon cross-border section will allow a 40% saving in energy, thanks to the easing of the gradient and the doubling of the load capacity, making rail transport competitive compared to road transport, with considerable resulting economic and environmental benefits.

In France, a Public Inquiry was held, coordinated by an independent commission, before the go-ahead for the work, which expressed itself both with regard to the benefits in realising the work and on the project itself. This procedure applies to all major public works and it involves all the interested parties (proponents, committees, citizens, experts and all those who wish to participate). In the case of the Lyon-Turin line, it ended with a favourable opinion.