Been working on New York State railroads. I built up, over the course of about six years, a database of NYS railroads, digitized off USGS topo maps and ortho photos. It is, for the most part, better than the TIGER data, but not everywhere. So ... I've been importing it all by hand, mile by mile, line by line, combining it with existing TIGER railroads, or in the case of abandoned railroads, existing TIGER tracks, paths, and roads.
I've finished with the Erie-Lackawanna. Other major roads still to be done include the LIRR, the LV, the NYC, the NYNH&H, and the Pennsy. Been working on the import since 2006, but only seriously since July of 2009. I still have 252 lines to go. At one a day (which is about what it takes), that's a year worth of work days.
New York is a BIG state, and it had a LOT of railroads. Specifically, the total number of miles in New York State that were ever graded for tracks is: (drum roll, please) 14811.17 miles.