Not a model one, but graph out a real network superimposed on a map of NYC. Or modify the existing one. See how your design stacks up. The simulation uses real-world data (census data, jobs data, existing transportation demand data, etc.) to determine how useful your design really is. Select your line from the box on the right, and click where you'd like to place a station. Unfortunately there's no means of controlling exactly where the resulting lines are situated (that I can see), but that's probably not the aim of the game. You can, however save your creations and re-load them into the game to continue working on your design in a later session.
Read more info here
Play the "game" here
For the example above, I merely extended the D train one stop to White Plains Road/Burke Avenue to create a transfer connection with the 2 train. This has actually been proposed a long while ago (the D-line's tunnel points directly at this intersection despite the map's appearance), and I myself know this would have been immensely handy on a number of occasions.
While this modification didn't change the system's overall "grade", in another session I was able to boost it to an 'A' by extending the Brooklyn end of the #2 and #5 to Nostrand Ave / Voorhies Ave in accordance with another long-ago plan (the 2/5 station at Flatbush Ave was designed as a through station rather than a terminus. It has been stated that the tunnel actually does extend for a short distance past the station and one of the capital plans suggested using the space for tail tracks (like those at 34th/Hudson Yards) to improve traffic flow in and out of the station)
---PCJ