I made a series of straight and intersecting highways with single and dual traintracks in between, to make it easier to line them up nicely. Each of the pieces can connect to each other directly. The straight highway pieces makes it very easy to draw longer stretches of highway and trainlines with proper spacing. The traintracks are elevated enough above the highway so you can draw connecting lines or stations to the side of them. All of the pieces are also available in the map editor, so you can set up your highway properly when creating a map. This will also save you a lot of upkeep costs, since you don't pay anything (obviously) for roads and trainlines created in the editor.

*I recently updated all of the most popular items to have in-game icons and tooltips. If any of these assets doesn't display properly in-game, let me know so I can update them. Currently there is a problem with the Asset editor, so I am no longer able to create or alter any of the traintracks, so I can't take any requests in regards to alterations or new assets.