One thing I would like to add is that public transport is too very difficult to scale. For example, the Northern, Central and Piccadilly lines on London Underground are massively overcrowded to the extent where it’s borderline dangerous.
I don’t really know what TFL can do about it, because the lines already operates at maximum capacity. They could build more lines at £15Bn each (http://www.cityam.com/279301/gbp148bn-crossrail-project-face...), but even if money grew on trees these projects take 5-10 years to complete, by which time population has grown so much that they too are overcrowded by the time they open.