Spine Line KC to St Paul - What type of freight?

How can I tell if a northbound train from Des Moines is going to stay on the Spine Line and continue north to St. Paul, or if it is going to switch to the West-East main line?

I live near Nevada, Iowa, near the juncture of UP's Spine Line (KC to St. Paul) and the main line (West-East) and I have always wondered if there's a way to tell if the northbound ones are heading all the way to St. Paul or if they're going to turn.

It seems that the main line has mostly trains where the freight is stacked intermodal or 100% hoppers or 100% tanks, while the Spine Line seems to carry mixed freight. Would a train that is 100% hoppers or tanks continue northward to St Paul? Would a mixed freight possibly turn onto the main line?

Also, do you ever talk to the yard crews? Would I be able to ask one of them where a train is going?

There is two manifest (all kinds of cars and freight) trains that come from Des Moines and "turn the corner" at Chicago/Kansas City Jct connector. One goes east to Chicago. The other is actually a turn that goes to Boone, exchanges cars and returns to Des Moines. There's one, maybe two (I don't keep up on the Short Line traffic out of DM. Short Line is what the RI people called the Spine.) that go north. Plus I think there's a local that works to and from Iowa Falls.

The UP currently doesn't run that much north out of Des Moines, except for trains that originate there. Most trains coming out of Kansas City going north (all kinds including manifest, empty grain, ethanol and sand) to the Twin Cities or NW Iowa grain lines use the ex MP to Omaha and then use the ex CNW east/west to Grand Jct (for NW Iowa) or KC Jct for the Short Line. The Short Line sees more southbound traffic.

Eventually that could change. There has been talk, long term, of double tracking the Short Line. In addition there has been revived talk about building a new yard over around Nevada to replace Boone, Marshalltown and Des Moines (for classification purposes, industry work would remain) yards.

Much appreciated! Thank you tons!

Would the manifest that turns east to Chicago look any different from a manifest headed to St. Paul? Would the manifest that turns West to Boone be shorter, since it's a smaller distance than Chicago or the TC?

If I were to be on a manifest train headed north out of Des Moines, what are the odds it would end up in St. Paul?