question

Hey @Lion, I actually think with the way you've setup your Process Flow, when the Green and Red Delays are both 0, the "Variable S1" is set to "1" for the majority of the time. The Trucks seem to generally need a value of "0" to pass, so of course they'll accumulate in front of S2.

The reason you're always going to get an increasing amount of content at the "Travel S1" activity is because you're spawning trucks faster than they can drive away. When you spawn a bunch on top of each other, they'll continue accumulating. The Network Nodes you're using can only have 1 truck on that road at a time because you have it set to "Non-passing" (the yellow arrow).

If you'd like to see 0 Avg.Staytime and 0 Avg.Content at S1, then you'll have to either (1) spawn trucks at a slower rate or (2) speed the trucks up so they get through the light faster. There are probably other ways, but those are the two that come to mind right now.