The ability of any user recognition system to provide a positive ID is paramount. Any registration process should be quick and simple; subsequent verification readings should be reliable. PIN codes are in themselves insecure, as they are easily revealed. Physical tokens - cards and tags - do not fair much better as they can be lost, stolen or cloned; they can get broken or passed on to others and used for 'buddy-punching'.
A unique biometric credential however - such as a hand - cannot be compromised. Hand geometry readers have a high read accuracy even in circumstances where hands become soiled; they are also the least invasive, and therefore the most widely accepted, biometric technology.
Traffic control, in the form of barriers, lights and audio-visual communication, provide the interface with the physical world and must form a dependable and secure barrier to unauthorised access. Any worthy system will also offer comprehensive management tools such as remote monitoring, audit trails, real-time tracking and Fire & Evacuation Muster control.