I've always thought of O.W.L as the Norman Rockwell of photography, and I don't say that to be pejorative. To me his photographs were about more than trains, but like Rockwell, he sketched out for the viewer how the community related to the railroad. Plus, he was unapologetic about his art and his methods. If there ever was a exponent of what could be called unavailable light photography it was him, and for our younger generation, he did this at a time when flash was non-electronic. The equipment he used was massive. Consequently, if you look at some of his famous images, like the one with the train crossing the bridge with the kids swimming in the stream under the bridge, the lighting was so extensive he must have needed a blasting permit to take the shot.
If you have to do a research paper about him I would recommend limiting the scope of your paper to some specific aspect of his life and how his work related to his contemporaries. May I suggest a title such as: O. Winston Link, Industrial Photography at Mid-Century. The idea would be to examine industrial photography during that time frame and show how it influenced his work.
Denis K