Life Cycle Assessment of Maillart’s Bridges

Robert Maillart’s contribution to the community of civil engineers and, most of all, his crucial role in the evolution of the structural art are undeniable. He was able to merge not only mechanical efficiency with innovative solutions but also aesthetic expression as a real artist, always balancing his choices with limited resources both in terms of construction materials and costs. Following these three key parameters he succeeded in producing structures which can be considered a very good combination of structural performance and sustainability. The actual goal is to understand to what extent Maillart’s bridges are indeed sustainable in addition to be efficient and elegant. That is why performing a Life Cycle Assessment (LCA) of his bridges is a valid quantitative confirmation of his achievements. The followed procedure is, thus, based on the computation of construction materials volumes. Starting from the original drawings, elaborating them as 3D model, the contribution of concrete and steel is computed. Then, the volume of masonry is also calculated and, where present, the timber for the scaffolding. The goal is to compute the Global Warming Potential (GWP) of each bridge, to normalise them per deck area and to be able to compare them according to different strategies. The amount of equivalent carbon dioxide (kg CO2e) is computed as a linear combination of each structural material quantity (SMQ) with a relative Embodied Carbon Coefficient (ECC). Moreover, considering their structural scheme, their foundation soils and all the geometrical parameters of the decks and arches, it is possible to gather different bridges and to find relationships according to the similarities of emissions of each class. The main results are found in the structural and soil properties. First, in the correlation between GWP only due to steel with respect to the total one of each bridge and the amount of steel for each static scheme. Then, in the average values among two macro groups of terrains which make the bridges to assume similar GWPs within these macro classes themselves.