Representation and Construction of Skewed Masonry Arch Bridges in England between 18th and 19th Century

Between the eighteenth and nineteenth centuries, in England, the impressive development of railway lines imposed a careful reflection on the construction of bridges to cross roads and canals. Particular attention it was paid to the possibility of using skew arches. This wasn’t a new structural element, but nevertheless needed a renewed theoretical and methodological reflection to define an appropriate structural model and make it easy to apply. The wording of a theory on oblique arches saw the engagement of engineers, mathematicians and architects at that time. As part of the methodological exemplifications relating to the construction of such bridges, the contribution of representation is a fundamental and indispensable element, which not only facilitates the reading and understanding of the various formal configurations, but even guides its constructive practice. By analyzing the original documentary sources at the base of the different applications and theorizations, the paper intends to underline the close interconnections between representation and form and show the contribution of visualization to the practical education of workmen in this specific field. These evidences were achieved through a process of graphical analysis of the drawings related to the theories of various authors, from Peter Nicholson to Charles Fox, from George Watson Buck to Edward Sang.