Mr. Dresser presents a pretty good picture of the arguments for and against, but glosses over one very important piece: the Federal Transit Administration's Cost/Effectiveness criteria.
It is generally accepted that, for the FTA to approve the Feds' 50 percent of a transit project, the FTA C/E score must be below $22. Alternative 4C is about $31 (I don't have the DEIS in front of me right now). There are other cities with more-cost-effective proposals on the table that will get funded before the Red Line will. The MTA appears to be banking this entire project on the assumption that Barack Obama will significantly liberalize the FTA criteria upon taking office.
And nevermind that - the $1.6 Billion cost is heavily inflated due to the high cost of tunnelling Downtown - the oldest and most geologically unstable part of the City. Does anyone really think a NEW Downtown tunnel will come in at or under the projected cost? How is the State going to pay for the inevitable cost overruns and delays that always happen with projects like this?
I'm ALL for vastly better transit in Baltimore. But the reality is that tunnelling is exponentially more expensive now than it was when most of America's subways were built - even DC's. In a time of catastrophic budget deficits, I think we need to think long and hard about whether the time savings of an underground tunnel are really worth it.