To protect the bunker, a security system with sensors was installed in the walls of the vaults, which reacted to shocks and noise. When an alarm was triggered, the local police were automatically notified, but they did not know what was in the bunker. Only the director of the installation could enter the bunker and listen to noises in the vault by means of an intercom. The vault itself could only be accessed by a few employees of the Bundesbank from Frankfurt, as the associated keys were not stored on site.
