A framework for integrating embodied carbon assessment and construction feasibility in prefabricated stations

With underground increasingly used for accommodating infrastructure and transport networks, construction sustainability throughout the life cycle of projects attracts growing attention. Specifically, to achieve decarbonisation goals, there are two types of strategy in the early design and construction stages: optimising material usage and designing with low-carbon materials to build clever, and utilising low-carbon construction technologies and minimising waste to build efficiency. Integrated solutions that consider environmental impact and construction feasibility become increasingly important. This paper incorporates building information modelling (BIM) to evaluate Greenhouse Gas (GHG) emissions and construction practicality while enabling design adaptation. A solution for adaptive designs of underground stations with variable geometries is achieved, which collectively explores carbon accounting and construction viability. Under the emerging contemporary design and modular construction approach, a multiple level-of-details (multi-LoD) prefabricated station is developed to verify the proposed framework. We focus on calculating embodied carbon of the prefabricated station at the product and construction stages according to EN 15978:2011. Then, automatic quantity take-off of all elements presented in the model is achieved by enabling data/parameter assignments and processing in BIM via visual programming. Five parametric adaptions with a fixed width are made to compare the contribution proportion of components to carbon emission. The difference in carbon footprint contributed by changing the steel reinforcement ratio is the highest. Two use cases were further evaluated for construction feasibility and investigation of the beneficial potential of the integrated solution for large-scale metro network expansion. The first case verifies the interoperability between the multi-LoD BIM model and numerical modelling for a station at the construction stage with known ground conditions. The second case demonstrates the on-site BIM-based construction simulation with selected carbon solution for a station on a planned metro line. This paper explores the implementation of information modelling and enhances interoperability for the planning and construction of sustainable underground infrastructure.