Following the handover of the civil engineering buildings and structures in the period from May 2020 until January 2023, the installation of the general services and technical infrastructures has started at the HL-LHC worksites of P1 (ATLAS) and P5 (CMS). The two worksites are in the so-called worksite Category 1 and will remain closed and independent from the operational accelerator complex until the completion of the vertical cores, that will link the LHC tunnel to the HL-LHC galleries in summer 2026. the technical infrastructures concern the installation of the electrical distribution (cable trays, general-service cabling, lighting, transformers, switchboards…), the cooling and ventilation systems (cooling towers, water pumps, piping & valves, ventilation units & ducts…), the alarm and access system, the transport equipment (cranes, lifts, hoists…), and the doors and operational safety equipment (fire extinguishers…). The four underground safety exits (the UPRs) have been fully equipped during long shutdown LS2 and delivered to LHC operation to guarantee a safe interface between the LHC and the HL-LHC during beam operation throughout Run 3. The installation in the surface buildings is progressing according to the general master schedule. The infrastructure installation in the cooling buildings (SF17 and SF57, see Figure 1) and in the helium compressor buildings (SHM17 and SHM57) is nearing completion and the commissioning of the two SF buildings is planned for summer 2023. The commissioning of the cooling and ventilation buildings (SU17 and SU57, see Figure 2) is planned for autumn 2023 at P1 and for spring 2024 at P5. The completion of installation in the electrical buildings (SE17 and SE57, see Figure 3) is scheduled in January 2024 at P1 and in summer 2024 at P5, while the two SD buildings, including the Oxygen Deficiency hazard (ODH) detection will be completed by end 2024.

Following the discovery of concrete spalling in the joints of the concrete modules of the lift shaft at P1 in February 2023, the installation of the lift has been stopped to consolidate this non-conformity and to ensure safe working conditions for the lift installation team. The installation schedule has been modified by installing first the lift at P5 which will be completed by July 2023 and by resuming the installation of the lift at P1 in September 2023, following the consolidation of the concrete modules.  This issue has delayed the completion of the installation of the underground infrastructures which require accesses via the lifts by several months.  This delay should not impact the start of installation of other machine equipment, in particular the installation of the QXL cryogenic line in the new UR galleries, which will commence in August 2024 at P5.