That PIRG report has made its rounds and now a group in Pittsburgh wants to use the evidence from it to kick off a campaign to take rail from Pittsburgh to Oakland, the neighborhood. It is the third largest downtown center in Pennsylvania and has many Universities and a top notch medical center. It's also where Mr. Rogers began discussing his neighborhood at WQED.
It's also not connected by any of the rail lines or busways that Pittsburgh has built over the years. Given the previous cost estimate of $750 million dollars 15 years ago, I'm imagining this 2-3 mile expansion will be a subway. The layout for those not familiar is below. The orange is the existing light rail which includes a downtown subway and tunnels in the hills. The red is the east busway, the first 6.8 mile section was completed in 1983 at a cost of $115 million ($244 2007 or $36M per mile) and the yellow is the currently under construction North Shore Connector which will open up the north side for rail expansion. It's a rather hilly landscape and like San Francisco, one of the reasons the light rail lines were saved is because of their tunnels.