I'd also recommend a visit to Yahoo Groups and joining this one (851 members):
Ed
This is where railroad historical societies really play an important role, and the SR has a good one, with a useful website. Note the photo gallery. I suggest you join.
http://www.srha.net/default.asp
Note also that they have back issues of their magazine for sale. I'll wager there is a wealth of photos and articles that would interest you.
http://www.srha.net/public/TIES/ties_magazine.asp
Dave Nelson