Thanks for all of the information.
The railroad episode was interesting. I think, since the last time I read up on National Security, in California you cannot be stopped from photographing any publically available from public land structure, unless it says so first hand, such as military installation or some things like that. You can get questioned, but you don't have to say anything nor do you have to produce any ID or other identification.
The reason I know this is because I was at a marina last year photographing boats. There happened to be a Coast Guard cruiser docked nearby. One of the hands came off of the boat and asked me what I was shooting? I said, "Boats." Then he said, "Why are you shooting boats." I said, "Who wants to know?" He said, "Well, with national security and all it's my duty to ask you." I said, "Do you think if I were a terrorist I would tell you I was photographing boats in order to blow them up?" He said, "No, of course not?" I said, "Well, since you can't arrest me nor do I have to answer your question, what's the efficacy of this conversation?" He then proceeded to ask if I had a business card, which I thought even more silly--terrorists don't have cards for situations like this I guess. I told him I did but he didn't need to see it for the same reason I just gave. Then he asked if I lived around the area. I told him it was none of his business and if he didn't leave me alone I was calling the local police. He stopped after that.