Train nerd called TETSU-OTA

When I am waiting for the train on a platform, I sometimes notice there are people who just stay there without getting on a train.

They are standing on the edge of the platform, hanging a big camera around their neck. When the train comes in, they snap shutters madly.
They are called TETSU-OTA, which means train nerd.
TETSU is short for TETSUDO(train), OTA is short for OTAKU(nerd).

I don't know why they are so fascinated by the train.
I like the window view from a train, I like tasty Eki-ben(the lunchbox sold at each station, which has own regional characteristics )
However, I've never been fascinated by a train itself!

<em>[Excellent.  I've always been fascinated by riding new trains or looking at pictures of old ones from long ago.  I can't quite understand why you would snap pictures of a train that passes through the station every day.]</em>