I still think that a priority system is an important feature:
it was more than one time already that just the wrong wares got transported when there was much traffic on some road segments.
Right now there is no way to influence this which is very bad. I really liked the priority system in Settlers II - it worked very good and I don't remember that it had any bad influence.
Your idea doing it with a kind of penalty and don't make it absolute seems for me indeed the best solution here.
I still think that a priority system is an important feature:
it was more than one time already that just the wrong wares got transported when there was much traffic on some road segments.
Right now there is no way to influence this which is very bad. I really liked the priority system in Settlers II - it worked very good and I don't remember that it had any bad influence.
Your idea doing it with a kind of penalty and don't make it absolute seems for me indeed the best solution here.