I printed out an Elevated Track for my City. I designed all the parts parts for the El and then found the ones for the Passenger Platforms. Here is the link to my post: Link to Elevated Post
I used NX to develop the models, exported them to .stl, and then used Simply3D to print them out. I talked to a professional friend that I know does modeling for his company and he said to use Simply3D to set up the model and to print it out.