When we think of bridges, it is the dramatic and monumental long spans that come to mind first, especially the lithe suspension bridges such as the Golden Gate and the pure geometric arches such as Sydney Harbour. But the majority of bridges are not such spectacular structures. Most of them are ordinary overpasses, with spans of 30 or 40 feet, carrying roadways or rails across other thoroughfares or over small streams. You see such bridges by the dozen on any drive down the Interstate. They may be lacking in glamour, but they are more representative of a bridge builder's art.
The engineering and construction of girder bridges are pretty routine these days, but the bridges are not quite standard items you order from a catalogue. The girders, whether of steel or concrete, are custom-build for each bridge, then trucked to the site and hoisted into place with a crane. The designer still has scope for variation and creativity, and it shows out on the highways: some overpasses are prettier than others.
Engineers seem to have a clear, if usually implicit, model of the process of design. It is usually an orderly model of an orderly process as the engineer conceives it.
The notion that the design process should be modeled as a systematic step-by-step process seems to have first developed in the German mechanical engineering community.
Herbert Simon independently argues for design as a search process in The Sciences of the Artificial. He was motivated to lay out a strictly rational model of design precisely because such a model was a necessary precursor to automating design. His model remains influential even if today we recognize the "wicked problem" of original design as one of the least promising candidates for AI.
In software engineering, Winston Royce independently introduced a seven-step Waterfall Model to bring order to the process. In fact, Royce introduced his waterfall as a straw man that he then argued against, but many people have cited and followed the straw man rather than his more sophisticated models. Even if ironically, Royce's seven-step model must be considered one of the foundational statements of the Rational Model of Design.