Environmental influences on footbridge design

The form, material and style of a bridge, particularly footbridges, are influenc ed by the abilities and concerns of the society in which it was built. Today there is a need for environmental and sustainability issues as well as aesthetic and cost issues to be considered i n the planning and construction of a bridge. The author predic ts that the architecture and engineering of bridges around the world, and footbridges in particular’ will gradually change to meet these concerns, as their designers begin to understand the key issues involved.

To understand environmental issues there needs to be some sy stem of measurement. T raditionally cost has been the key parameter and can be a good quantati ve indicator of environmental issues. Other more qualitative methods for measuring the environmental aspects of a project have been developed in rec ent years. These consider, aesthetics, energy use, environmental impact etc. Both methods have shortcomings which are discussed in the paper. It is becoming more common now to measure directly, or at least estimate, the energy or carbon equivalent for a p roject.

Relative values are derived for cost and a qualitative environmental assessment for a set of European, US and SE Asian structures. The materials used vary from steel, concrete and a more modern plastic/composite material. The results are presente d. The validity and variability of the methods are outlined. The key issues of material choice, efficiency and localness are discussed in relation to the derived values. Differences between European, US and Asian results are reviewed. The possible traject ories of the architecture and engineering of such structures in the future is discussed.