Here would be my ideal system to seriously start considering:
Select portions of this track really need to be underground, through South Side's CBD, Bloomfield's CBD, Lawrenceville's CBD, and throughout the Strip District's CBD. There is no need to have this in-grade through Penn Ave, Butler, Liberty, or Carson. They would only have to bore underground in certain parts and then secure rights of way elsewhere.
The only part of town I think it could successfully be installed at-grade would be through Oakland. The streets are more than large enough and they could dedicate lanes and get them separated only for rail cars.
But if they can't find a plan to successfully give its own lanes and minimal disruptions, they should go ahead and plan to bore underneath Oakland as well.
THIS is what Pittsburgh needs, not some dreamy line to the airport and to McKeesport again.
They could also consider semi-24 hour service, such as running trains as late as 2:30am and starting back up again at 4:30ish, or do weekend 24 hour service. There are plenty of homes and bars and clubs that need to be serviced after hours, even on business evenings.
This new extension to the Pittsburgh subway and LRT system would be 9.5 miles, significant portions underground, and given how much money has been put into the north shore connector I think its a wise future investment. It would probably cost $3-5 billion to build a 9.5 mile looping system that has significant portions underground.
That's not a bad investment because the money only needs to be spent once, and it would secure Pittsburgh's future. We can fund $15 or $30 billion stadiums, yet we can't build a decent transit system?
LOL Yea, right... Especially when in the US we have such a generous system where usually 40-60% of funding always comes from the federal government (more if your Congressional delegation and Senators push for it).
I could easily see a system like this being funded 75% by federal funds and the remainder broken up between local and state governments.
Small price to pay for a new Pittsburgh. The Federal government certainly won't be funding any of the new dreamy stadiums that Pittsburgh has financed or the upcoming Penguins stadium.