Climate Impact Assessment of Temporary Works in Urban Infrastructure - A Case Study of the West Link Project, Gothenburg

Abstract

Temporary works are essential for the construction of permanent infrastructure but are often excluded from climate assessments and procurement requirements. In complex urban infrastructure projects, such as underground rail construction, these temporary constructions may involve substantial quantities of materials, transport activities and machinery use, resulting in potentially significant greenhouse gas emissions. This thesis investigates the climate impact of temporary works in the Västlänken railway tunnel project in Gothenburg and evaluates how well Trafikverket’s climate calculation tool, Klimatkalkyl, represents these impacts. Four temporary constructions were selected for analysis: a diaphragm wall system, a crane foundation, a canal infill and an aqueduct. A life cycle assessment (LCA) was conducted using a three-scenario approach. Scenario A represents a standard Klimatkalkyl calculation based on generic default values. Scenario B adds construction activities that are structurally absent from standard calculations while maintaining the same emission factors. Scenario C applies project-specific Environmental Product Declarations (EPDs), transport distances and fuel data. The results show that the significance of omitted construction activities varies substantially between construction types. For the diaphragm wall system, the addition of previously excluded machinery activities increased total emissions by only 0.1%, whereas the aqueduct showed an increase of 137%. Applying project-specific data reduced calculated emissions by up to 45%, primarily due to lower-emission concrete mixes and the use of HVO100 in construction machinery. The findings indicate that current infrastructure climate calculations may underestimate the climate impact of machine intensive temporary works and that a gap exists between reported and actual construction phase emissions. While Klimatkalkyl can technically accommodate these activities, the current procurement framework does not systematically require their inclusion. The study concludes that this gap is structural rather than a question of data quality or compliance, and that temporary works require greater attention in climate reporting and procurement if long term climate-neutral infrastructure ambitions are to be supported.