Shutting down half the line maybe is unlikely. They'de probably have to shut it down in smaller sections, but put shuttle buses in it's place during it's contruction. Yes, it would be a drag during that time, but in the long run it would be very beneficial. As for the trains, at least the new TR...

Anyhow, how does this sound?

A fine example of a subway using this type of track is the subway in Athens, known as the Athens Metro, a very fast subway.

Greetings.:) Besides the subway line extensions and new subway lines that the city needs, the tracks of the current subway lines need rennovation. In particular, to SLAB TRACK. Something like this: http://en.wikipedia.org/wiki/Slab_track#Ballastless_track The benefits would be faster...