How to add more trains?

I nearly always see a complaint bubble at my passenger train station complaining of a need to add more trains to the schedule. Unfortunately I can't see anything to do with adding more trains to the schedule. Is there a way to do this? And would adding another train station help?

Solution 1:

From the looks of it I got more trains/tourists by adding another train station at another corner in my city. But I dont have any recorded numbers to back it up.

I've looked but as far as I can tell there is no way to add more trains or otherwise increase the capacity. Editing the train station I see no upgrade, in contrast to the bus terminal where you can add additional buses.