Pedestrian bridges of different materials - Comparison in terms of life cycle cost and life cycle assessment

The need for more pedestrian bridges has increased over the years. The trend of producing sustainable solutions leads to the investigation of the structures in terms of the financial and environmental impacts. The purpose of this thesis was to determine the most cost and environmental efficient material for bridge construction. To achieve this, three bridges, two exciting bridges and one designed bridge, were selected and evaluated from a life cycle perspective. The requirements for bridge selection were to have free span with a length of approximately 19 meters. The materials that had been chosen to be compared were timber, steel and fibre reinforced polymer (FRP). Timber and steel bridge were selected while the FRP bridge was designed according to the same dimensions as the timber and steel bridges. Life cycle assessment (LCA) and life cycle cost (LCC) analyses were performed for the three bridges. LCC and LCA are two analytical tools which provide reliable estimations of the environmental and economic impacts during the life cycle of a structure. In LCC, the present value method was used, with regards to the recommendations from Swedish companies and authorities. LCA was performed using program Bridge LCA. This program provides a holistic view of the different emissions that can be emitted from a structure. Evaluating the results of different bridges provided reasonable information for the optimum solution. According to the outcomes of the analyses, the choice of the material can be decisive in the design of a bridge. The results showed that the main impacts in a pedestrian bridge derived from the initial phase, both for the LCA and LCC. Although the initial costs from the three bridges were similar, the most financial efficient material was timber in a life cycle perspective. In addition, timber was found to be the material with less effect to the environment.