The embodied energy and carbon dioxide emissions from the use of construction materials are among the concerns engineers must consider when planning, designing and constructing a bridge. Previous studies have been carried out on building structures to assess both the energy consumed and the CO2 emissions in their construction and use but less information is available to bridge designers. This paper outlines the range of embodied energy and CO2 emissions for materials commonly used in bridges and the variability of these values is discussed. A study is carried out for a moderate length river bridge of energy use and CO2 emission during construction. A number of different bridge forms and materials are considered. The primary forms are girder, tied arch and cable stayed. Three broad material groups were investigated, namely concrete, steel and steel–concrete composite. The study also estimates the continuing CO2 emission throughout the life of the structure from maintenance and repairs. From the study a number of broad trends are discussed and some design guidance offered for those wishing to provide more environmentally responsible bridges

The extradosed bridge can be thought of as intermediate between the girder and cable-stayed bridge forms. This paper explores the boundaries of this form of bridge to attempt to define them more clearly. The paper summarises previous work on extradosed bridges and outlines the authors' own findings from their parametric study of a bridge near the boundary between cable-stayed and extradosed. The key parameters of extradosed bridges are outlined and compared with those for girder and cable-stayed bridges. The study indicates that although there is a clear division between girder and extradosed bridges the boundary, if any, between extradosed and cable-stayed forms is less clear.

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It is over a century ago that testing of reinforced concrete slabs by the pioneers of the material such as Lord, Turner and Maillart showed that restrained slabs could carry significant loads. Since that time the interest in and knowledge of the internal arching, or compressive membrane action, that enhances the strength of reinforced concrete has waxed and waned. In this paper, definitions of key terms such as arching action, compressive membrane action and geometric arching are given. A review of key twentieth century research and testing is also given, with particular emphasis on aspects related to bridge decks. The more recent advances in compressive membrane action and punching shear are then outlined. A graphical summary of key tests is presented, together with an initial analysis of these data. The current American, British and European bridge codes incorporating compressive membrane action are reviewed and the major differences outlined in the light of this recent research. Finally the key issues are summarised and a few thoughts on future research and the codification of arching action and compressive membrane action are given