Access control vestibules are designed to prevent tailgating by using a set of interlocking doors where the first set of doors must close before the second set opens, thereby ensuring that only one person at a time can pass through the security checkpoint and that each person is verified before entry. Mantraps are another term for these systems, and are effective in stopping tailgating. A badge reader by itself cannot prevent tailgating unless combined with a physical barrier system like a turnstile or a vestibule. Biometrics authentication enhances security by assuring the identity of an individual but does not inherently prevent another person from following them. Keycard systems provide a mechanism for authentication but again do not guarantee that an unauthorized person can't follow an authorized user into a secured area.