Redesign and Upgrade of the LHC Access Control System

The old LHC Access Control System (LACS) was based on a single access control solution, which integrated software and hardware into one monolithic application encompassing all the different subsystems (access control, video surveillance, interphones, biometry, equipment control, safety elements). Both the hardware and software were approaching end-of-life by the vendor before the CERN Long Shutdown 2 (LS2). The new design is based on a distributed approach, where the different subsystems are integrated in a flexible manner with well-defined interfaces, which will permit much easier single sub-system management, upgrades, and even full replacements if necessary. From the system point of view, the focus is on the advantages that this redesign brings to system operation, testing, and management. Procedurally the interest is in the overall management of a very complex in-place upgrade of a system, where the new implementation needed to coexist with the old during its constant simultaneous solicitation over the LS2.