I have been a avid rail fan my entire life. My first cab ride was at 4 years old. I have photographed trains from coast to coast and have rode trains in nearly every state. I am still a rail road photographer and often go to very remote places where rail fans rarely go. So I will try to make a few points.
Long before 9/11 there was railroads that did not want photographers on their property. I grew up around Denver and the D&RGW wouldn't even let you take photos from their parking lot. If they caught you anywhere near their property they would chase you off and tell you not to come back. The Burlington northern on the other hand would give you a waiver, you signed it, and you could do pretty much anything you wanted. I used to go all over the locomotive taking photo's including walking on the roofs.
Times have changed drastically. I have personally been interviewed by the local police, homeland security, port police, State police, railroad police, and countless security guards. I have also been interrogated by locals who live in the area who wonder what I am doing. I was once followed by a Nebraska railroad cop from the Wyoming border all the way to North platte. Everywhere I stopped he would be sitting a half a block away.
I know that fighting the system is not going to work. So if you can't beat them join them right? And that is just what I did. Instead of pulling out a card with my rights as a photographer and demanding a lawyer. I instead went to the offices of the police department, railroad police, homeland security, and others and explained who I am, where I was likely to be on what day, and why I was there. I gave them all my information and signed anything they wanted me to sign.
Now when some jerk off rail road cop gives me a hard time, I tell him that I have already spoken and registered with the department of Homeland security, the Sheriffs department, the State patrol, and many others and that they can not only verify who I am but what I am doing there. I also explain to him that some of my biggest fans of my rail road photos are rail road cops, and managers in other states. He really can't say much after that.
My advice to other photographers is to make as many contacts as possible and get their cards. The more credibility you have the less they are going to care about you. Many of these people will consider you part of the security force once they trust you.