At least in Barcelona, the blocks are already there and have been since the end of the 19th century - they are just grouping the blocks into superblocks where t

At least in Barcelona, the blocks are already there and have been since the end of the 19th century - they are just grouping the blocks into superblocks where through traffic is only allowed on (on average) every third street and the rest are car free (I imagine residents can still use them).