Since the district began weighing every lorry at the check post on the northern approach, the number of overloaded lorries booked there has fallen to a fifth of what it was. Yet the district's roads are breaking up at the rate they always did, and the road office's own survey finds the same weight of stone moving into the district each month. Which of the following, if true, best accounts for these findings taken together?

Fewer bookings with the same stone arriving and the same damage being done means the overloaded lorries are still running but are no longer passing the scales. A bypass through a village that the post does not watch produces exactly that: an emptier register and a district carrying the same weight as before. Larger scales would catch more lorries, not fewer. Rail traffic might explain the stone but leaves the roads' continued breaking up unaccounted for. A heavier fine would be expected to reduce real overloading, and so makes the unchanged damage harder to explain, not easier.