In 2005 an upgrade in screening technology and rising security concerns led to luggage-screening processes being conducted behind closed-doors, as opposed to them being done just before check-in previously within public view. Carry-on luggage and persons screening are conducted at the individual departure gates, while check-in luggage are screened in the backrooms and secured before loading. A perimeter intrusion detection system for Changi Airport's perimeter fence has also been put in place to further strengthen security of the airfield. while a biometric access control system for staff movement has been put in place since 2006.