http://www.post-gazette.com/pg/09074/955761-52.stmMost people when first hearing of the proposal to extend the Light Rail system to the North Side first asked "Why not Oakland?" for the obvious reason the second and third biggest transit stops in Pennsylvania is downtown Pittsburgh and Oakland section of Pittsburgh (downtown Philadelphia is #1 in the state). These two area are only areas are only two miles apart. The main business district is Downtown Pittsburgh, while the University of Pittsburgh, Carnegie-Mellon University are all in Oakland (As are most of the Hospitals, UPMC). It makes perfect sense to connect Oakland to Downtown Pittsburgh via a Light Rail system, but why the option of crossing underneath the Allegheny River to get to the North side has NEVER fully been explained (I suspect developers, Oakland was filly developed by the 1920s, the North side was destroyed when Penndot finally finished the Expressway to the North Hills leaving a lot of land to develop that previously had been low income housing.
Another explanation was to increase access to the Stadiums, a third explanation is bureaucratic, i.e. "The Light Rail System has successful in the South hills, lets expand it, and it looks like it is cheaper to build it over to the North Side then to Oakland." hard to say why this was started and now it has run out of money and support (Which it really never had among the Public).