How to get traffic moving

I felt sure there was already a thread about this, but if there is, I can't find it.
I have traffic enabled in Environment, but I don't see a single vehicle in my game. What do I have to do? I am using roads that I have always used before in TANE, that always had traffic on without my even telling them to.
Build 116960, Macintosh, trs2019.

Maybe have a look at this post;

https://forums.auran.com/trainz/showthread.php?167642-Why-no-road-traffic&p=1921764#post1921764

Quick instructions on how to use here;
https://cdetrainz.com/tutorials_grid_region.aspx