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We fully agree with Professor Gauvreau’s assessment that Robert Maillart’s Salginatobel Arch Bridge (Figure 1 a) is a beautiful structure (Billington, 1983), and we would also agree if he had argued that the inverted form of the Salginatobel Bridge by Christian Menn called the Gante Bridge (Leonhardt, 1984) is a beautiful bridge (Figure 1 b). However, we disagree with his assessment that the bridges of today can be lumped together as a group of extravagant structures whose owners, builders and architects paid no heed to the need for economy, clean efficient load paths and aesthetics. In fact, we believe the opposite is true. We believe that the synergy created by the interaction of various disciplines such as engineering and architecture leads to better structures. Some structural engineers are gifted artists; however, they constitute the exception, not the rule. We would argue that architects, by education and training, are taught to be sensitive to aesthetic considerations, whereas structural engineers, for the most part, are not like the artists who work in 3-D forms such as architects and sculptors.
In general, we believe that the collaboration between engineers and architects leads to outstanding structures as was proved in Fazlur Khan’s John Hancock Tower (Mufti and Bakht, 2002) in Chicago.
Another point on which we disagree with Professor Gauvreau is his position that “clean efficient load paths” have been sacrificed for ”flows of forces that are indirect and inefficient.” To suggest that the design of the Esplanade Riel Bridge (Figure 2a) is based on indirect flow of forces is patently incorrect. The tower of this bridge was not inclined to attract attention. The inclination was dictated by the flow of forces caused by the eccentric semi-circular platform, which incidentally was a functional requirement of the citizens of Winnipeg.
We believe that the advances made in innovative materials such as fiber reinforced polymers and structural health monitoring have allowed major changes to the design of structures, which were not possible previously. In fact, one of the points that Professor Gauvreau makes is that engineers should utilize innovations and apply them to new structures such as was done by the “technical innovation” that “in turn gave Maillart new opportunities for visual expression.” From our point of view on the one hand, Professor Gauvreau wants engineers and owners to embrace innovation to improve the economy, durability and aesthetics of a structure, and on the other hand he criticizes the engineers, architects and owners who have applied these principles in the construction of the Esplanade Riel Bridge.
The Esplanade Riel Bridge is a beautiful structure, which incidentally meets the aesthetic criteria discussed by Billington (1983), Leonhardt (1984) and Ohata (1987), being:
Lightness and thinness
Exposed and undistorted
A form that fits the local environment
Winnipeg is a city built at the confluence of two great rivers,the Red and the Assiniboine. The Esplanade Riel Bridge evokes the image of a sailing ship at safe harbor on a river. It has been well received by the citizens of Winnipeg and has become a landmark in the skyline of the city.
Professor Gauvereau notes: “when structural systems are determined on the basis of preconceived notions of what will look good, the effect on cost can be significant. When the premium that is paid to create a specific aesthetic statement is in the tens of millions of dollars, one is certainly justified in questioning what was gained for the money spent.” Such a statement is made by ignoring the fact that there is huge difference in the costs of a monument and a purely utilitarian structure. A restaurant in the middle of the Esplanade Riel Bridge was intended to be a feature of bridge. The City of Winnipeg wanted this structure to be an icon to attract tourists and boost the local economy, which it has done. Comparing the cost of this icon with the cost of a parallel vehicular bridge is like comparing apples with oranges. It would be more accurate to compare the cable-stayed Esplanade Riel Bridge to Santiago Calatrava’s contemporary and unique cable-stayed El Alamillo Bridge in Seville, Spain (Figure 2b).