Architects are increasingly getting involved in bridge design, an area traditionally dominated by civil engineers.
This week we ask: Is architectural input vital to attractive bridge design?
Richard Galloway, director, transportation, Parkman
First, I have to declare an interest, since my father was an architect, and this subject has caused lively filial debate in the past!
An attractive bridge is a blend of science and art. It will be functional, having structural economy and low maintenance; but it will also be pleasing to the eye in terms of shape, use of light and shade, and attention to detail.
It is very often the landmark bridges which we focus on, but all bridges can benefit from better attention to detail. The arch bridge is the classic example where functional solution governs form, but many could have been improved by better consideration of detail.
Engineers are driven by practical considerations. They are concerned with economy of structural performance; buildability; and maintenance implications. Too often the engineer hides behind the argument of cost and yet good attention to shape and detail should not cost any more.
The danger with all this is that it results in thinking in straight lines - both literally and metaphorically. Architects, on the other hand, are unfettered by such constraints. They focus on shape; texture; the interplay of light and shade; and the 'human' perspective and detail.
The answer is a marriage of both, with the project being led by the engineer, supported by input from the architect. I would certainly not advocate the reverse of these roles!
I believe that the problem lies in the difference in our educational and training backgrounds. The engineer comes from a predominantly science base, whereas, very often, the architect has an arts bias.
There is no doubt in my opinion that engineers can benefit from being exposed to architectural thinking.
There are two ways forward: either we demand greater artistic awareness of our engineering graduates at the outset, or we accept that the best engineer is the practical engineer focused on delivery. In the latter case, in my view, we will continue to require architectural input to our designs.
Godfrey Webster, head of bridges, Owen Williams
The ability of a bridge to meet its functional requirements has to be the major criterion of design. These include the static and dynamic loads, impact and span requirements, as well as the good detailing required to enable the survival of the bridge in a hostile environment.
Within these limits there is often a wide range of possible solutions. In a society with limited resources the choice has to be mainly an economic one, because this determines how many problems of inadequate bridge links can be solved, or what other social priorities can be addressed.
Aesthetics must come as a lower priority but this is not a recipe for boring or ugly bridges. Following the principles of Sir Owen Williams, it is my experience that an economic and functional design with simple detailing will lead to an aesthetically pleasing outcome. Aesthetic principles should be taught to engineers, and indeed have been a part of good degree courses for generations.
Engineers should be aware of the dramatic impact on the landscape their work can produce, and the ways to make that impact uplifting rather than soul destroying. But they should also be wary of the subjective and fashion driven side of aesthetics, and avoid being swept along by this at the expense of economy and simplicity of form (eg Tower Bridge, the proposed Borough Viaduct and the winning Poole Harbour entries).
Engineers' understanding of the properties of materials in the short and longer term puts then in a better position than architects to control the design process. Architects and particularly landscape architects can make a contribution at sensitive sites, and then should be involved from the outset of design, not to 'embellish' finished designs.
However the problem of a missing bridge link is an engineering problem with an engineering solution.
The Millennium Bridge now under construction across the Thames is one example of a bridge designed by a team of engineers and architects - in this case Ove Arup & Partners and Foster Associates.
Engineers have traditionally dominated bridge design, notably on projects like Clifton Suspension bridge, Sydney Harbour Bridge, the original Severn Bridge, the Humber Bridge and the Queen Elizabeth II crossing at Dartmouth.
Engineer Flint & Neill and architect Dissing + Weitling Arkitektfirma designed the winning entry in the Highways Agency's Poole Harbour Bridge competition in 1995.
Millennium Bridge information available at: www.arup.com/ MillenniumBridge