I wonder if there is some kind of "steady state" vs "transition" effect that could explain this though. For instance, if you put up a sign that changed the spee

I wonder if there is some kind of "steady state" vs "transition" effect that could explain this though. For instance, if you put up a sign that changed the speed limit from 70 to 80 but changed nothing else about the road, would you see an initial increase and then decrease after a few miles? Although I'd also guess that in reality if the speed limit changes to 80, there's probably other characteristics of the road that change so that the steady state might not regress back in this instance.