Just exactly where are we in the whole scheme of things? There may have been a point that "cutting losses" might make sense. I would speculate we are already past that point by quite a bit. 
As much as I feel our money has been spent ineffectively, I doubt it would be prudent to as you say cut our losses. It would be more like a cut our throats to do so at this point. 
Cutting losses might be the tough stance, but, it would be the wrong stance, or, are you too blinded by what has transpired to this point. 
We NEED the rail, we just need to pay as much as it is costing, and for that, I agree with you, but, to cut losses is very short-sighted.