This permitting process has been going on for several years.

Question - Why did UP (or any railroad) need county approval to add a second track?

I know there is a potential issue with a Native American treaty and some potential restrictions because it is in some kind of federally designated visual protection corridor and involves wetlands, but why is it that the count planning board/commissioners are the ones approving this? And why did UP even bother applying with them? I think we all know this is more than a siding extension as it involves extending the existing siding into multiple main track for a moderate distance which might allow for some rolling meets or stacking trains.

So does the county intend to decide how many cars and trucks can use paralleling I-84?

You can pretty well guess this is going to end up in federal court but I'm not sure when it is all over UP still ends up with some restrictions placed on it.