Integration of the HL-LHC machine and its services within the existing LHC tunnel: Challenges and proposed approaches for the integration of a large-scale project

The High Luminosity Large Hadron Collider (HL-LHC) project is a major upgrade of the LHC presently operating at CERN, designed to enhance the performance reach in terms of integrated luminosity collected during its operational era by another order of magnitude. It involves the replacement of the entire machine and services over more than 200 meters on each side of the high luminosity experiments of ATLAS and CMS, and other modifications across the entire LHC complex. In this context, the HL-LHC Integration team is responsible for the optimization and validation of the new machine layout to ensure an efficient installation, ease of maintenance, and effective system operation. The paper focuses on the challenges of this integration task, in particular for gathering the information and the models to produce accurate 3D assemblies of the overall project, and identify and manage conflict resolution between different teams. This includes the coordination of several equipment groups and related design offices, adapting to spatial constraints of the existing infrastructure, managing equipment at various stages of their design, and dealing with interfaces between existing and new infrastructure. The team employs a combination of 3D design tools and agile management strategies, such as interactive progress-tracking tools (Kanban Board), scrum, sprints and feedback loops. The integration relies on a complete 3D model from which the new reference Layout drawings and database are derived when design milestones are achieved. Integration releases through robust documentation approval and archiving systems constitute the installation baseline.