The Art of Bridge Design

Abstract

Early 2017 I read an old book that shed a new light on the writing of this dissertation. At that time I had been working on my dissertation on and off for over five years and the end was not in sight. Ever since I took a part-time position as a lecturer in 2012, I had been engaged in a balancing act between two busy jobs, having one foot in the academic world and one foot in practice as an architect and designer of bridges. At first, teaching and working with students gave me a lot of energy and opened my mind to new ideas, and was as such very beneficial to my work as an architect. However, the combination of working two jobs and writing a dissertation as well proved no easy task. Even though I managed to write some journal papers during brief bursts of writing frenzy, I had become aware that the balance between work and family life had imperceptibly tilted to the wrong side. By the end of 2016 it became clear to me that my inner machine needed a major revision. I needed time for myself to think about the further development of my career(s), so come Christmas eve I took a six week break from work. To distract my mind, I started reading Henri Gautier’s ‘Traite des Ponts’ [1], the very first comprehensive handbook for bridge designers (figure 1). My fellow board member of the Dutch Bridge Foundation and a fervent Francophile, Jan de Boer, had lent me his first edition from 1716, a beautiful leather-bound specimen with intriguing engravings of bridges, details of joints and depictions of various tools employed in the art of early eighteenth century bridge building. I have always had a fascination for old books and history and I was curious about this fellow bridge designer from the time of Louis XIV. Despite the old French language and the somewhat different typography, the ‘Traite des Ponts’ turned out to be surprisingly accessible reading material. Reading the Traite provided me with a whole new lens to look at my dissertation subject. In fact, looking back on my subject across a bridge of three hundred years proved to be a very good remedy against my writers block. Henri Gautier (1660-1737), who was sometimes referred to as Hubert Gautier, was an architect, engineer and inspector of the ‘Corps des grands Chemins, Ponts, & Chaussees du Royaume’, the erstwhile corps of engineers for roads and bridges at the service of the king of France. From his own rich working experience, Gautier writes about a discipline that he and I both share. For an engineer in the service of the king, his writing is remarkably down-to-earth. He writes very spontaneously and with plenty of self-reflection about his metier. I especially enjoyed discovering parallels between Gautier’s practice and the current bridge building practice. Gautier wrote his Traite out of dire necessity as he had noticed that not a single architectural author had so far concerned himself with the art of bridge building. To his frustration only sideway glances on the subject of bridge design were offered in the literature of those days and he wondered how a schooled architect was supposed to learn the art of bridge design if his training was deprived of the right books on the subject. He further notes that even the great Vitruvius, the Roman architect of antiquity, doesn’t dignify to write on the art of bridge design. For this reason Gautier took it upon himself to collect what little had been written on the subject and to comment on it. More important however is that Gautier shares with us his own practice experience acquired through the many bridges he had built in his lifetime. It is interesting to note that Gautier does not write to impress the reader with the vast extent of his knowledge. Rather he writes out of a personal motivation to share his knowledge, dedicating his work to ‘those that are ignorant’ (on this specific subject, red.). Gautier deeply feels it to be his duty to share his experience, describing the tools and the means that he employed to come to a bridge designs, all in a way that makes it easy to understand. According to Gautier bridges are ‘amongst the most difficult of structures (to design and to build, red.), deserving our full attention, and belong to a domain of Architecture where there are the most precautions to keep, more place to fear and to doubt, and to which one can never take too much care’. At times, reading the Traite was like a deja vu; the parallels to my own practice brought a smile on my face. I found it most refreshing to note that a certain amount of friction between architects, engineers and contractors appears to be of all ages. Gautier doesn’t hold contractors in a very high regard. According to him ‘Contractors do not hesitate to enrich themselves at the expense of the King or of those who work for them. Engineers or inspectors of the works, on the contrary, have only in mind the honesty with which they act and [the desire red.] to be highly esteemed. They do not hesitate to regard the former as their enemies, when they are unfaithful.’ (p.248). Nowadays, it is fortunate for all parties involved in the building of a bridge that the laws and fines imposed for building faults have been adapted to modern times, as can be appreciated from this fragment on legal guaranties. ‘If the structure is made out of earth or out of a mediocre material, a six year warranty must be given and in case of a fault committed by the contractor, the law indicates that said contractor shall be whipped, shaven and banned.” (p.225). Gautier however finds these laws to be unjust as he believes that the responsibility for a fault should to some extent be shared by the architect if it is the design that is to blame. These amusing notes set aside, Gautier concludes his preface with the following recommendation that I choose to quote in Gautier’s original words: ‘Le sujet des Ponts est assez vaste pour donner de l’occupation aux plus habiles. Jusqu’ici personne n’a traite de cette matiere autant qu’elle le merite. J’ai ose l’entreprendre, & je souhaite que quelqu’autre fasse mieux, afin que tout le monde en profite davantage.’ I would translate this ancient French text as follows: ‘The topic of Bridges is vast enough to give occupation to the most skilled. So far no one has dealt with this subject as well as it deserves to be treated. I have dared to undertake it, and I wish someone else would do better, so that everyone can benefit from it to the full.’ Three hundred years later, reading this very personal recommendation from a fellow bridge designer opened my eyes. What more encouragement did I need to write a dissertation on the topic of bridge design! And like Gautier, I have undertaken this task to the best of my knowledge and experience, hoping it will benefit those who choose to venture in the challenging art of bridge design.