initialize

Puts the resource back where it was declared, at the start of every replication.

Without this a replication began wherever the previous one stopped. The context restores membership between replications -- an agent added during model construction stays a member -- but nothing restored a position, because the position was set once in an init block that runs at construction and never again. So replication 1 started at the declared point and every replication after it started whereever replication 1 happened to end, silently: the run completes, the statistics look plausible, and only a model whose answer depends on where vehicles begin would show it.

This is the same defect a manifest surviving a replication is, and it has the same shape: an interface cannot enforce it, so the class that owns the state has to be a ModelElement and override this. Membership is re-established defensively as well, so that a model which removed the resource from its context mid-replication still starts the next one whole.