Railroad Tycoon 3: Get the hell off my rails!

For Christmas I got Railroad Tycoon 3. It was noted how much I enjoyed Sid Meier’s Railroads! except for the part where it crashes my machine every single time I play it-- so I rarely play it.

So, I’m playing for the first time, the Boston to Buffalo campaign on Easy and I see that I can’t connect rails side to side. Why the hell can’t I? Not even putting a double rail down, then connecting from there. It still connects to the existing rail going out. I must be doing something wrong.

But the thing that really pissed me off was that the AI connected to my station in New York and then proceeded to use my railways into Hartford. It didn’t build new rails next to mine, it used my rails. And then, with it’s connection to my station in New York, prevented me from laying track leading out of New York because his track connected to mine and I couldn’t lay track on my own damned railroad.

Tell me this was something funky I did and that I can build off tracks and the competition can’t use my rails and prevent me from using my own lines?