Pittsburgh is faced with two different projects. One, the Maglev project, is supposed to run from the airport, through downtown, out to Monroeville and Greensburg using a maglev train. A different project is an extension of the T line under the Allegheny River to connect with the two stadiums.
Which one to do? Probably neither. There is definitely not the demand for a high speed Maglev here in Pittsburgh, especially considering that USAir may be gone by the time groundbreaking occurs. A better option there would probably be to build a Las Vegas/Los Angeles line. You'd actually have demand on both ends of the line; ultimately it'd probably end up paying for itself.
Digging a tunnel under the Allegheny River? Not really necessary either. Who's going to take it? It's pretty easy to walk to the stadiums from downtown on game days, so it's not going to service downtown traffic. People who park at station square are probably going to continue to take the ferry boats across the river on game days. That leaves everyone south of town with access to the T who is willing to take the T to the game, not very many people.
If the money's going to be spent to dig something, a better use would definitely be to run a line out to Oakland, allowing commuters who ride the T to be able to take it all the way to Oakland without having to get out and take the bus. Students would also be able to take the T to Station Square, a popular destination. In essence, build a line that will be used daily, not a line that will only be used during game days in the summer and fall and not at all in the winter and spring.
Ideally, the money should be used to support the above ground services of the Port Authority (the bus system) which continually raises prices and cuts back on services. When will the government learn that the more people take the bus, the less problems they have with traffic congestion and pollution?
This really should be a moot point. Does the city government not realize that Pittsburgh is almost bankrupt as it is? Do we really need to be spending any more money expanding the T or building a maglev when we can barely cover police and fire services?