Hi,
If you want to see streets, individual buildings and tracks, try and get a Sanborn Fire Insurance Map of the south Bronx. Library of Congress and New York Public Library map rooms have copies. So does Bronx County Historical Society library. Sanborn maps are also available to private subscribers online, but pricey.
I don't have a reference handy, but RAILPACE magazine did an article on transfer facilities in the Bronx in the late 1980's. You might contact them for a copy of the back issue or xerox of the article.
Roger