Railroadradio.com (or is it .net? .org?) iPhones don't have the radio pickups to actually recive the radio frequencies used by the Railroads (and Emergency Services for that matter). I'm unaware of any SmartPhone that has such capabilities. There are a few Android out there that can get AM&FM frequencies and you might be able to get others with them, however I haven't looked to much into those phones. There may, however I highly doubt it, be an app & add-on device for iOS that can receive such frequencies, but again I doubt it. If so it would be an App and a plug in (similar to the FM transistors).
Truthfully your best bet is to just pick up a radio and carry that around with you.
peter