In a recent article (I cannot remember if I read it in the Post-Gazette or Tribune Review), Peduto stated how he would like to work towards expanding Pittsburgh's regional public transit system, especially its light rail system to serve places in all directions from Downtown.
I, too, share this vision, especially with Pittsburgh, Allegheny County, and the region as a whole growing again for the first time in decades. The South Hills are already well served by two LRT lines that provide service to Library, Bethel Park, Mt. Lebanon, and Castle Shannon to name a few places as well as Downtown. An extension to the international airport has been discussed for years, especially with the recent growth that has been taking place along the Parkway West corridor. Cranberry is one of the fastest growing communities in the country. Both are just a couple of places that could benefit from increased public transit service to Downtown Pittsburgh. I haven't even touched base on Oakland, the Allegheny Valley, or other parts of the region.
Above, I put together a map that I created in Google Earth. For right now, I foresee an expansion of the existing Blue and Red Lines. The Blue Line would run from Library, PA through Downtown and along an alignment through Allegheny Center and up through the North Hills to Cranberry. The Red Line (renamed Green Line) would run from South Hills Village in Upper St. Clair/Bethel Park and eventually out along the Ohio River to the Airport. I see three additional lines. A yellow line would run from the First Avenue station and run parallel to the Monongahela River to Bradocc and from the Steel Plaza station up through the Strip District to Highland Park. For the eastern neighborhoods, I envision two heavy rail lines. The Red Line would follow an alignment along Fifth Avenue from Steel Plaza to Oakland and East Liberty to Forest Hills. The Orange Line would extend from the intersection at Fifth and Penn, following Penn Avenue through East Liberty, the Strip District, and into Downtown eventually crossing the Allegheny River directly beneath the Clemente Bridge, directly serving Allegheny Center and the Mexican War Streets. In the map, I have both of these lines extending further, but for right now, I don't think this part is very feasible.
I also have a vision for a regional rail network providing service to places like New Castle, Beaver, Butler, Greensburg, and Washington, PA. I will post this map in the very near future.