The people of Atlanta need a lesson in Econ 101 and need to read Duranton and Turner's paper called the Fundamental Law of Traffic Congestion. To my friends who teach Economics at Emory and Georgia State, I would ask you to write some local editorials on this topic. Micro economists must educate voters about what we know and what the voters should know before they make an irreversible policy choice.
I know of no economic evidence supporting the claim that improvements in public transit without simultaneously introducing road congestion charges will reduce traffic congestion. The demand for trips when you face a zero marginal cost for road use is quite high.
It is important to note that Duranton and Turner were not paid to write their paper on transit. I bet that the boosters of the public transit projects have hired consultants to write paid "research" to document that improvements in public transit reduce highway congestion. Are any of these papers good? Could they withstand peer review and actually be published? Do the funders care? I care. There is an element of adverse selection here so that the people who read Atlanta's newspapers view all Ph.D. economists as perfect substitutes. But, are we? Who is the intellectual 1% and have they earned the right to be taken "more seriously"?