What these studies also don't include is the *real* cost of operation. The cost of roads from the city's perspective doesn't include the cost of all that gas that is burned by everyone's cars (not to mention car maintenance). So the real cost to city residents for rail is orders of magnitude cheaper.
Not only that, but when we start having oil shortages (probably starting next year) railways (which can be powered by electricity) will suddenly seem like the only practical solution. Building roads inevitably leads to more oil/gas consumption and we're already far too dependent on oil.
Also, when you widen a road or build new ones you tend to get more people moving into the area with the newer/wider roads (because of the reduced traffic). This means more demand for city resources (water, anyone?) and... Increased traffic! Building and widening roads is like putting a band-aid on a wound that requires stitches.
Then there's the disaster scenarios: If a big hurricane blows through Jacksonville there will be many, many trees down blocking roads (and quite possibly requiring road repairs). Removing debris from a railway is a lot quicker, less resource-intensive, and cheaper than removing it from roads (meaning you can get back to our lives faster). They even have special railway cars to clear it all up in one go.
-Riskable
http://riskable.com"If you elect leaders that act irresponsibly towards nature, you'll find that irresponsibility is the nature of your leaders."
"If you don't like traffic stop having so many kids!"