Options on the TrainPlayer Preferences Switches tab:
Barrel
through when closed: determines what
happens when the train comes to an impassable switch (see picture): check
this box if you want the train to go right on through the switch without
changing it.
Minimum
angle to open: smallest angle between
two tracks at a junction which permits the switch to open. For
example, in this picture, clicking on junction 1 toggles
between the main line and the branch as expected; clicking on junction
2 has no effect, because the angle to the branch is too steep
(less than 130 degrees).