Following the Official Journal of the European Union and the selection procedure based on financial and economic and technical capacity, a number of main contractors will be set up on the basis of the “most economically favourable call for tenders”. Each of the main contractors has the necessary skills and supply chains to carry out the different aspects of the construction work during the period covered. At each call, it is decided whether a mini-competition is necessary, depending on whether the conditions need to be refined. . . .