One of the problems is that the grid in Barcelona is quite imperfect. A similar plan to prioritize bus transit across orthogonal lines has been far from successful, and my take is that one of the reasons is that orthogonal lines have ended up not being quite orthogonal at all.

Anyway it's been the policy of the city government at least from the 90s to reduce the surface area dedicated to the cars. Interestingly most of the recent interventions have been on what would be on the superblocks concept considered 'fast' streets (mostly by increasing the side of the sidewalks [Arago, Balmes St, Diagonal, General Mitre] and by reorganization massive intersections [Glories, Lesseps].

And there are a few committed plans also in this direction [Via Laietana, Urquinaona].

So there are really two competing visions here:

* Make "fast" streets more pedestrian-friendly, kill urban highways, make the grid work in a homogenous way, increase surface for pedestrians across all the city. * Create a hierarchy of streets (with fast/slow streets)

And to me it's far from clear which vision is going to win.