I recall a story about a woman whose father was a fanatic about trains. For several years she lived in Paris. Her apartment was nice but her living room overlooked the switching yards of the Gare du Nord.
When her Dad came to visit he was riveted to the front window and exclaimed, 'What a marvelous view!'
I have fellow-feeling for this gentleman. I'm a railway fanatic myself, especially for the old-fashioned and quaint aspects of trains-and-railways. In my teens, I spent several months in Paris, supposedly to learn about French culture / literature / art; but what I found most interesting and delightful about that stay, was the local railway scene.
My brother is a fairly cool character, not really given to nerdy traits. (Over the years, I've done a lot of boring him with my railway obsession, which on the whole he endures patiently.) He gets plentiful fun from musing on, and fantasising about, the "nerd phenomenon". He says in jest that if he were ever to become a nerd, he'd fancy the hobby (which I gather, does actually exist -- and why not?) which revolves around all aspects of barbed wire: the different "shapes and makes" of the stuff, and which of same are favoured in different parts of the world, and the history of the different sorts.
Brother also talks of inventing a brand-new nerdy pursuit: his latest idea in that line, is a passionate interest in Sellotape (American, Scotch tape), in all its different varieties, from different countries -- including assembling a large collection of samples of the assorted kinds.
And, I have a friend who collects banknotes (American, bills) -- not to spend, but to cherish and keep (they have to be in perfect mint condition). He is interested in the differing serial numbers on the notes: wants to have one of each, which means a totally unattainable goal -- that being in itself part of the fun. What with my own kinds of nerdiness; I feel I'm in no position to mock...