To speed up trains between Chicago and Joliet the Trib is reporting that it would cost 1.5 Billion Dollars. That is Billion with a B, or to think of it another way you could have a 10 person business jet operating at $2,500 per hour transporting 10 people or about $250 per hour per person. It is a one hour flight from Chicago To St. Louis roughly. So you could fly 6,000,000 people or the current last minute fare is about $300 so you could fly 5,000,000 people one way.
Not sure if the 1.5 Billion is cost effective.