Inspirations in footbridge design

I start with some general comments on the engineer’s design process and how it changed historically from standardization to “structural art”, from 19 th century conciseness to free forms. Today, with an increasing number of project requirements, good design has to be synthetic in the sense that it is fulfilling sim ultaneously multiple options. In a best case, design is based on a precise concept, written in a few words or sketched in a rough form, providing the basis for taking all the subsequent decisions. According to Edgar Allan Poe’s detective novels, for findin g a synthetic concept it is the hypothesis, the paradigm, which precedes empirical investigation. When designing bridges, an efficient procedure is using “images” as a starting point. Images show a complex reality at a glance. Images are strong tools, beca use they are synthetic. Images can be tested by applying falsification. The list of requirements acts like a type of sieve where useful images need to pass through. If an image proves to be promising, in the further design process it will be transformed to fit more and more the specific needs of the project. When images are appropriate, they include a large number of simultaneous solutions, like an integral function. Therefore, inspiration in engineering means finding and transforming useful images.