In a statement, Porto Metro said that "the international public tender jury will now examine the admissibility of the proposals submitted".

The base price of the competition is more than €221 Million and the award criterion is the “lowest price”.

The company or consortium that wins the maintenance and operation contract is going to receive the sub-concession for a period of seven years, starting in April next year.

Via Porto has been run the Porto Metro operation (formed by Barraqueiro, Arriva, Keolis and Manvia) since 2010 and the contract expires in April 2018.