Out of curiosity, what will light-rail do for this city?
A downtown circulator system could be a forerunner of less surface parking...
I agree with Artist that just installing tracks could be an expensive failure without proper planning. Now is the time to start the planning.
I see 3 levels of potential rail.
1. Streetcar/trolley as a circulator downtown. Provides a method for people to get from the light rail or heavy rail station to the place they want to go. BOK Center to Blue Dome and Brady would be a start. Then expand to Cherry St and Brookside if the projected ridership is there.
2. Light rail would go to nearby areas like the outer reaches of Tulsa itself or the nearby suburbs. Routes using existing rail would probably have to be heavy rail due to regulations about mixing light and heavy rail. I am thinking of a Broken Arrow route or using the mainline to Tulsa International. The New Mexico Railrunner would be an example of this. I think light rail would have a greater chance for success if much of it could be grade separated like the trolley system where I was pre 20 yrs old. It would be difficult to get that much ROW. The system where I grew up was put in when it went through the boonies from western Philadelphia to the county seat in Media, PA. Most of it is filled in now.
3. Heavy rail (except as above) would include farther places as OKC, Dallas. Hopefully it would be high speed enough to make it more attractive than driving a car or waiting an hour and a half in the airport for a 50 minute ride to Dallas followed by trying to rent a car.
All of this would depend on having enough potential riders to make it work. Without enough riders, even a bus system would fail.