http://www.nytimes.com/2011/06/06/business/media/06transit.html?_r=0
Alex Morgan Bell proposed an application that would run in the background of many smartphones and track when the phone lost service and when it reconnected to a cell network. By using the input of many phones and processing algorithms, the app may be able to tell what train a phone has taken and locations of various trains.
Example of Automated Train tracking
https://itunes.apple.com/us/app/subwayarrival/id402247424?mt=8
The Trains operated by the central computer are numbered while Driver operated trains are shown in black because the current line of the train is unknown to the computer.
Earth Cam time square:
http://www.earthcam.com/usa/newyork/timessquare/index.php?goto=live