Since we know that demand for mobility is unlikely to decrease, the only solution a shift towards vastly more efficiency transportation systems -- public transportation. But then the time constraint kicks in, hence my earlier remark on subway/tramway line construction times.

I don't know what to think about this, given, as you said, how central political commitment is. The point is not really to forecast what may take place but to understand what is actually possible if there is a strong political will. Madrid, seems to be a clear case. What impact can we expect overall?

Rien n'est gratuit en ce bas monde. Tout s'expie, le bien comme le mal, se paie tot ou tard. Le bien c'est beaucoup plus cher, forcement. Celine