Early estimation of bridges with regards to LCA. Parametric design study of three bridge types with regards to LCA

Abstract

This study utilizes parametric design to determine cross-sections and quantifying materials, including their corresponding CO2-equivalents, for single-span bridges, making it easy to identify the most suitable option from a LCA perspective. This is interesting because the Swedish construction sector accounts for a total of 21 % (Boverket, 2023) of the ecological footprint, which corresponds to 48 million tons of CO2-equivalents. Traditionally, experience-based dimensions are employed for efficient and rapid design according to our supervisors at Inhouse Tech AB. However, this compromises the bridge’s full optimization regarding design loads and resistance, which is not ideal from a CO2 perspective. As a result, this study has developed a programmed tool for each bridge type (deck slab-, prestressed girder-, and composite bridges). Where users simply input the width and length, and the output provides specific materials and their carbon footprints. This study investigates specific carriageway widths of 6, 9, and 12 meters and every other meter for span lengths from 6 to 40 meters, to provide guidelines on which bridge type out of these three is most advantageous in terms of LCA. The results show that slab bridges are more suitable for shorter spans when considering LCA. However, the choice of bridge type for longer spans varies and is highly dependent on the width of the carriageway.