Dealing with project complexity requires counterintuitive thinking. Complex systems are unstable and their sensitivity to initial conditions makes them unpredictable. There is no methodology that controls this uncertainty and little prospect of projects regressing to a simpler state. Consequently we must learn to live with doubt.
Projects have a tendency to become saturated with risk and some of it is dark risk that can only be detected at a late stage when multiple systems are allowed to interact and do so in unexpected ways. Berlin Brandenburg Airport provides a stereotypical example.
The problem with large, complex projects is two fold: