Correct, in single player it's possible to control trains.
Wait on a track for a train.
Then jump on the train and kick off the engineer.
Now you have the actions accelerate, brake, ring bell and use whistle.
But in the video, there is an additional action to switch tracks:
Hi,
if you enter a train, you have several actions: ring bell, use whistle, brake, accelerate.
I found a video:
In this video, there is an additional action: switch tracks.
Anyone know, how I can activate this action?