Answer to Question 1
PtD causes designers to think through what workers will actually have to do in constructing the permanent features of a structure. If any aspect of the design creates a hazardous condition the design is altered to eliminate or mitigate the condition.
Answer to Question 2
Heinrich's theory has two central points: 1) Injuries are caused by the action of preceding factors; and 2) removal of the central factor (unsafe act/hazardous condition) negates the action of the preceding factors and, in so doing, prevents accidents and injuries.
Structure of a salt wedge estuary.
The structure of the rib cage.
Structure of the H-R Diagram
Structure in the Universe
Interventions to promote safety for children
Vienna: Social Structure and Social Interaction