  Causal diagrams are logic and graphical tools that depict assumptions about
presumed causal relations. Such diagrams have proven effective in tackling a
variety of problems in social sciences and epidemiology research yet remain
foreign to civil engineers. Unlike the traditional means of examining
relationships via multivariable regression, causal diagrams can identify the
presence of confounders, colliders, and mediators. Thus, this paper hopes to
introduce the big ideas behind causal diagrams (specifically, directed acyclic
graphs (DAGs)) and how to create and apply such diagrams to several civil
engineering problems. Findings from the presented case studies indicate that
civil engineers can successfully use causal diagrams to improve their
understanding of complex causation relations, thereby accelerating research and
practical efforts.
