Fuller's Flyover in Guilderland, NY

[husky257]

At on time I found a pretty detailed explanation for the reson for the Fuller's Flyover in Guilderland, NY on CSX Selkirk subdivision. I was wonder if anyone had any information as to why this was done. I know that it goes back to the days of the 4 track main and how the freight traffic was split from the passenger traffic if Hoffmans, NY, CP 169 presently. Any information or links to information on this would be appreciated.