Digital twin aided sustainability assessment of modern light rail infrastructures

This study aims to evaluate the whole life cycle performance of Precast Advanced Track (PCAT) light rail systems in a digital twin environment, which is time-saving, flexible, and highly accurate. Two sustainability aspects of the system are addressed: environmental and economic impacts. In the life cycle assessment (LCA), energy consumption and CO2 emissions are calculated, whereas costs at each stage were calculated and converted to present values in the life cycle costing assessment (LCC). Revit is used for assessment. It enables the bill of quantities in the models to provide quantitative data for sustainability assessments. In the PCAT light rail systems, all structures and components have been considered, including subbase, concrete slab, rail fastening, rails, bituminous layer, rubber pad, and grease lubrication. Results exhibit that concrete slabs for street and off-street systems have a minor contribution to minimizing energy consumption, CO2 emissions, and costs. Rail fastenings and rails can be recycled, but the energy consumption is relatively enormous. Unrecyclable materials such as bitumen and grout account for a large portion of lifecycle CO2 emissions and costs. Surprisingly, these two materials are quite sensitive to parametric change. Accordingly, the digital twin confirms that PCAT concrete slabs demonstrate a good performance throughout the whole life cycle. However, there is still room for improvements, for example, re-designing a concrete slab with less grout while showing good waterproof performance. These structural modifications can be updated on the digital twin to enact positive changes for the sustainable development of light rail systems.