It is necessary due to the termination of the current plan, the PGM, which after more than 40 years (during which it was flexible enough to accept the introduction of hundreds of amendments and the development of a diverse range of planning instruments) is no longer capable of meeting new challenges.

It is desirable in order to ensure that the rules of the game and the priorities of urban and territorial planning are clearly defined and that the objectives of the various agents involved are in alignment with each other. The adverse effects of not having an up-to-date and ambitious plan need not be explained.

Finally, implementing such a plan is now possible, thanks to the confluence of three key arguments in its favour that seldom occur at the same time. First, the practical planning experience gained by technicians and government bodies in recent years, which they have shared with schools and universities, has resulted in the existence of human capital with the level of knowledge that such a challenge requires. Second, the advances made in information technology and scientific knowledge are now sufficient to make it feasible. Finally, it is politically, legally and administratively practicable thanks to the Barcelona Metropolitan Area Act, passed by the Parliament of Catalonia in 2010, which granted the powers necessary for the preparation of the plan.