I rarely see it, but I have seen double-stacked intermodal loads in the middle of manifest consists. Why exactly do they do this and what are the advantages exactly?
As a guess, it might be a bad order car that was set out, repaired, and then put in the first train headed to its destination.
Playing catch up so to speak.
CP Trains 290/291 carry double stacks as part of their mixed consists between WPG & Chgo. Normally on the head end of 290 to set off at Shoreham and on the rear on 291 for quick handling at WPG
Seemed to be pretty common on Norfolk Southern through Fostoria, Ohio back in July 1996.
http://www.youtube.com/watch?v=mFu1_Pg2cxc
http://www.youtube.com/watch?v=6ZbT_pUpLxI
http://www.youtube.com/watch?v=Jx6cVeb_0aQ
Kevin