Saltypaws, if you don't mind me asking, how did you put the subways in?
I'm not Saltypaws but I put subways on community lots by going to build mode, using the build tab, and clicking on the "Community Objects" icon on the upper right. It's in the "miscellaneous objects" tab (three dots on the tab) there. It's in the second row for me and has the LN icon (green plumbob in a pink circle) on the lower left of the picture. I have no problems plopping them down wherever there is enough room (7x4 if I recall correctly).
If there's not a community lot where you want the subway station, you can put in the smallest lot possible (10 x 10 unless you have mods) where you want the station via Edit Town mode and then build on the lot and put down the subway station. Make sure to name the lot while in Edit Town mode so that your subway station will have a name and you'll know where you're sending your Sims. (E.g., I have a Poker Flats station, a Puddlewick Park station, and a Bayou Gulch station as well as stations on already existing community lots like the Riverside Sports station, Twinbrook Town Center station, Twinbrook Wellness Center Station, etc. in Twinbrook.)
[Edit: If you have problems placing a subway station or other objects, try "moveobjects on". I often need to use that when in build mode. You can turn it off after you're done building.]