Set-Based Design: A Method for Improving Requirement Definition in the Bridge Procurement Process: How Set-Based Design Can Manage Uncertainty in the Preliminary Design Phase and Procurement of Frame Bridges

Abstract

The Swedish Transport Administration (STA) has committed to achieving climateneutral infrastructure by 2040, necessitating sustainable decisions early in public infrastructure projects. To strengthen decision-making in the preliminary design phase, managing uncertainty is crucial, and one approach is to implement Set-Based Design (SBD). This thesis investigates the application of SBD in the early stages of bridge design to address uncertainties and improve requirement-setting in procurement. A Python script was created to define the design space of bridge designs, which were presented as normal distributions of key variables: Material Cost, CO2-eq emissions, and buildability. Interviews were conducted to identify how the information gathered by SBD can be used in decision-making during preliminary design and public procurement. Findings indicate that the normal distributions can help decision-makers early in infrastructure projects, particularly in public procurement. By providing distributions of key variables, SBD can assist the STA to include award criteria based on both emissions and price, rather than solely on price. The research highlights the potential of SBD to generate absolute threshold values in non-mandatory requirements and added values for evaluation criteria in tender documents to consider tenders’ emissions in tender evaluation. The study’s findings suggest that adopting SBD can lead to significant improvements in managing uncertainty, supporting better decision-making, and advancing sustainable infrastructure development.