God allows poor engineering
Human engineering is an imperfect science. It is interesting to hear all of the Calvinist/Armenian debates erupt over the bridge collapse in MN. Mostly centered around John Piper's insistence that God is sovereign over catastrophes like this.
I think that God gives us the freedom to engineer. He however does not usually supplement our engineering efforts with miracles. Why did God allow the bridge to collapse? Most likely because the human effort to overcome the laws of physics failed.
How often do we place our faith in human efforts, then turn and blame God when our own efforts fail us?