Train line priority - set a main line option

I have 3 train lines in parallel. The lines on the left and right have stations. I would like to designate the middle line as a main line and have trains use this line by preference to the other two. This way I can queue up trains who want to go to a station without blocking trains which are passing through.

Factorio does this automatic by considering any station to count as a - I think - 1000 units of track for the calculation for routing. So trains will prefer any line without a station by default.

Same! I want to be able to have a "through" path with no station, and then sidings for stations that don't dead end. Right now the train goes through the station even though I don't want it to.

As a proposed solution, I would like to designate tracks as "priority track" and the train reserves some X amount farther ahead as a normal track segment.