Go to:
http://memory.loc.gov/ammem/collections/habs_haer/ (LIBRARY of Congress)

Look for the Browse Collection header,
select subject then yards!!! Includes maps as well as photos, mysteriously with a fair number of freight cars.

Delaware, Lackawanna & Western Railroad, Scranton Yards
Baltimore & Ohio Railroad, Mount Clare Shops

Plus others

Don't get lost for too long ;)

Jim