The Brief The Project Development and Environmental Study is examining the potential expansion of the commuter rail from Osceola County into Polk County. FDOT officials updated city and county leaders about the possible extension of the SunRail commuter train from Osceola into Polk County. Dig deeper:Some aspects county leaders are paying close attention to include the feasibility of the service, costs and ridership. As Polk County continues to grow, the state is considering alternative transportation options. This project has been a decade in the making in Polk County.