I have drifted away from posting info about national or general news unless I feel there is a lot of relevancy locally. This would be one of them, if only because I did similar research in graduate school on the subject. The basic gist is that the researcher took data from bus and rail systems around the country and found that bus ridership increased up to four percent and rail up to eight percent for every ten percent increase in gas prices.
My report was a bit different in that I used only the rail system in Dallas and measured ridership against other factors like fare increases, rail expansion and economic recessions as well as gas prices and found only gas prices had any significant effect on ridership one way or another.
I don't think the concept is that advanced. Prices go up, people shift to another product that is cheaper, simple economics. The trouble is that transportation is not subject to pure economic forces. Human behavior is a big factor, particularly when talking congestion. When you consider that some economists peg the U.S. government subsidy for gasoline over $10 a gallon, it certainly is time to reconsider the current model.