The project to adapt the Astigarraga-Irún line to the international track gauge with the installation of a third rail involves complex adaptation of all aspects of the existing line. This is particularly the case with the Gaintxurizketa tunnel, where an innovative tunnel boring machine, specially designed to allow trains to pass through, is playing a key role in the works. For the works on this line, ADIF has commissioned a team of Ineco engineers and technicians to undertake the project, management and technical assistance.