I suppose alot of the answers posted b4 mine have pretty much graced the highlites. to us, the ones who would have reason to watch a seamingless meaningless string of odd shaped objects roll by might to you seem a lil strange. the original word for train watching is rail fanning. from the word fan. just the same as nascar fan, olympic ski jumping fan, or yes, even nfl football fan.
the only difference is our balls come with 4500 horsepower (each!). they arent made of pigskin yet our balls are made of steel! our balls have shaped and made this country, not tossed around on parts of it on sunday afternoons for people to watch. our balls make pleasing sounds when honked and shake the earth when they go by. you can never hear/feel a football do that.
so you see, were a fan of something, just not something youd care to watch go by. i am glad to see a female respond with such a positive attitude towards trains. if its any insight as to what it is that we see, ponder this.....
i personally have been around to see railroading go from all male to actually meeting my first all female railcrew. i saw a change, right before my eyes. as an 'outsider' ( one who doesnt watch trains) this might not seem like anything new for these times. but thats what we see. the change of the country. and the world. most of todays traffic is container cargo. alot of that comes and goes overseas too. some of those trains are powered by new and different locomotives. now and then, a female at the controls!
to you an Amtrak train looks like a loco and a few passenger cars. on average a stander by couldnt tell a baggage car from a caboose. those in the know, know that that baggage car is more than likely older than the one looking at it. it has history. railfans dig history! certainly as an innocent bystander just walking down the street and you see a restored steam locomotive goes across a crossing, tell us you wouldnt look? i think you would. its something you dont see everyday. to us, each train that goes by, is like that. each locomotive, each car, each sound and smell is unique and different. right down to the face in the cab smiling back at you!
to you, 2 longs, 1 short, and 1 colorful long blast on the horn might trigger (and it should BIG TIME!) a train is very near! VERY NEAR! we hear those miles away sometimes. it has the same effect on us with digital camera, as a fireman and dalmation does to a firecall.
when ya boil it down, its just a fascinating unexplainable enjoyable love of just something simply ordinary. it is what each of us makes it. and everyday 1000s of train roll by. my how times are changing!