Maps and arterial roads.

It can all look good on the map. The pathway seems clear. You have a system– what can go wrong on the way from here to there? It is only when looking closely – or when trying to work out why you are in the wrong place – that the complexity becomes apparent, and the weaknesses inherent in the system obvious. The road that you planned to take is blocked by an accident, the side street which you then find as a way out is clogged by parked cars, and then everyone decides to use the bus lane to keep more lanes of traffic moving.