Automatic number plate recognition (ANPR) is a technology for automatically reading vehicle number plates. The Home Office states ANPR is used by law enforcement agencies in the United Kingdom to help detect, deter and disrupt criminality including tackling organised crime groups and terrorists.
Vehicle movements on UK roads are recorded by a network of 11,000 cameras that read around 60 million number plates daily. ANPR data is collated from all police forces into a central database and retained for a period of one year, at the National ANPR Data Centre (NADC), which can be accessed, analysed and used as evidence as part of investigations by UK law enforcement agencies.
The Conservative – Liberal Democrat Coalition government placed ANPR under statutory regulation through the Protection of Freedoms Act 2012. This established a right in law to collect the data, and placed controls on its use, storage and access by third parties.
The ANPR CCTV network
In 2005, the Independent reported that by the following year, the majority of roads, urban cetres, London's congestion charge zone, ports and petrol station forecourts will have been covered by CCTV camera networks using automatic number plate recognition. Their report said already in use cameras in some areas were being updated to feed data to a new centralised network, as part of a national surveillance strategy.
"What we're trying to do as far as we can is to stitch together the existing camera network rather than install a huge number of new cameras," - Frank Whiteley, ANPR steering committee chairman
Whilst some covert cameras are in use, most are standard CCTV cameras that were modified to be able to identify number plates. All British police forces were to be given dedicated ANPR vehicles, with all the data generated being fed The National ANPR Data Centre.
National ANPR Data Centre
The National ANPR Data Centre stores all ANPR data feed from the various police forces, currently it does not take data from CCTV networks in the UK. It is based at Hendon in north London, on the same site used for the Police National Computer. In March 2006 the National ANPR Data Centre claimed they could store 'reads' of up to 50 million number plates per day, with plans to expand capacity to 100 million reads in subsequent years. Vehicle sighting data is by default stored for two years. At the present 27 million clocks a day, over 18 billion ANPR records would be recorded every year. According to the National Policing Improvement Agency 25,000 hits per day against the ANPR database generate a transaction against the Police National Computer.
Crosschecks
The National ANPR Data Centre is connected to the Police National Computer to provide up-to-date lists of vehicles connected by the police to crimes. Other crosschecks will include insurance-industry data to identify uninsured drivers, vehicles without a valid MoT test certificates, vehicles who have failed to pay for valid vehicle excise duty, and/or with vehicles with unlawful number plates.
The National ANPR Data Centre allows analysis across police force boundaries. If a vehicle enters the ANPR network, the police should receive a photograph of the vehicle entering and leaving the zone. As the data generated is stored for two years the police argue criminals could be identified and linked to vehicles.
Data mining
The National ANPR Data Centre will make it possible for software to data mine previous sightings of license plate to identify patterns in the data. Patterns can be used to build up intelligence of a vehicle's movements on the road network or to find cloned vehicles by searching the database for impossibly quick journeys.
"We can use ANPR on investigations or we can use it looking forward in a proactive, intelligence way. Things like building up the lifestyle of criminals - where they are going to be at certain times. We seek to link the criminal to the vehicle through intelligence. Vehicles moving on the roads are open to police scrutiny at any time. The Road Traffic Act gives us the right to stop vehicles at any time for any purpose" - Frank Whiteley, Chief Constable of Hertfordshire and Chair of the ACPO ANPR Steering Group
The database
The National ANPR Data Centre uses Java software in conjunction with an Oracle database, using closed-access intranets instead the internet to transmit data. The system will be designed to work with possible future electronic vehicle identification marks on the bodywork of cars.