How does automatic number plate recognition work?

How does automatic number plate recognition work?

Access control and traffic monitoring are vital for both private security and public law enforcement. In addition to helping the police identify suspicious or stolen vehicles, traffic monitoring cameras help private businesses prevent unauthorised entry, reduce human error, streamline their access control processes and deter opportunistic criminals.

Automatic number plate recognition (ANPR) systems use cameras to read vehicle registration plates and cross-reference them with database records. But how does this technology work, and how can it be used for traffic monitoring, car park management and business security? Find out more below.

What is automatic number plate recognition?

Automatic number plate recognition (ANPR) is a technology used by law enforcement agencies, local authorities, the Department for Transport and private companies to read vehicle registration plates. ANPR uses this information to create location data, which is then shared with a centralised data system. This data can be cross-referenced with databases that contain vehicle records, such as police databases that record vehicles that may have been involved with crimes.

ANPR cameras can also ‘tag’ vehicles by creating a non-unique reference number for that registration plate. The same vehicle will be tagged again when it passes another ANPR camera, allowing local authorities and private companies to calculate journey times and car park usage. This information can be used for traffic monitoring and access control purposes.

How does ANPR work?

An ANPR camera will take an image of a vehicle’s registration plate. The ANPR technology will then read the vehicle registration marks (VHMs) on the plate, identifying the characters using Optical Character Recognition (OCR) software. Finally, once the letters and numbers are identified, the image is converted into machine-encoded text data using the OCR software, allowing the data to be checked against database records.

In addition to capturing and saving registration plate information, ANPR cameras will boost security by providing constant monitoring. Therefore, suspicious activity can be recorded and saved for future use in investigations. Plus, to provide clearer images, many ANPR cameras will use infrared illumination.

How is ANPR used?

ANPR technology is commonly used by law enforcement agencies (such as the police), the Department for Transport (DfT), local authorities and private companies. As such, ANPR can be used for a wide range of purposes, including:

  • Finding stolen vehicles
  • Average speed checks
  • Car park management
  • Private business security
  • Access control
  • Solving major crimes
  • Detecting untaxed and uninsured vehicles
  • Bus lane enforcement
  • Tolling
  • Traffic monitoring
  • National security and counter terrorism
  • Identifying minor traffic offences

Let’s take a closer look at the main uses of ANPR below:

1. Law enforcement

The police use ANPR to “help detect, deter and disrupt criminal activity”. This can involve any level of crime, from minor traffic infractions to major criminal offences.

One everyday use of ANPR is to check the average speed of vehicles on motorways. During an average speed check, an ANPR camera will take two timed images of the same vehicle, which can be used to determine the vehicle’s speed by comparing the locations. Speeding drivers will then be identified and fined.

ANPR technology can be used to solve vehicle theft by tagging vehicles in specific locations, and it can also be used to thwart more serious crimes such as terrorism threats. This is because ANPR makes it easier for the police to track wanted criminals or suspects. When a person of interest is identified, the police can stop the vehicle, search it and potentially make an arrest. Around 50-60 million ANPR records are submitted to the police by ANPR cameras daily, which shows just how vital this technology is for law enforcement.

2. Traffic monitoring

In addition to detecting speeding and other motoring offences, ANPR cameras are essential for traffic monitoring and control, especially along smart motorways. 

As explained earlier, ANPR cameras can ‘tag’ vehicles by reading their number plates and converting them into a non-unique reference number. When the same vehicle is seen again by another ANPR camera along another stretch of road, the same tag will be generated. 

The location of each tag can then be cross-referenced, allowing authorities to calculate speeds and journey times. This data is vital for the effective use of smart motorways, as it will inform the setting of variable speed limits and the opening of additional lanes when needed.

3. Security

Access control is a key part of business security. If you want to keep unauthorised vehicles off the premises, you need an access control solution that can quickly and efficiently identify who is allowed to enter.

By ‘reading’ vehicle registration plates and cross-referencing the data with a business’s database of authorised personnel, an ANPR camera can rapidly identify whether a vehicle should be granted access to the premises. If the ANPR camera is compatible with industrial gates and security bollards, this will create an efficient access control system that immediately allows entry when an authorised vehicle approaches, which will improve traffic flow in busy areas.

As well as denying entry to unauthorised vehicles, a private business’s ANPR system will also record any suspicious activity on the premises. Not only will this create solid evidence in the event of a break-in, but it will also deter opportunistic criminals as they are less likely to attempt a break-in if a business has visible security features like CCTV cameras.

4. Car park management

Just as ANPR cameras can tag vehicles along smart motorways, they can also tag them as they enter and exit car parks (both private and public). Monitoring vehicles in car parks is a fantastic way to improve car park management, traffic flow and payments.

As ANPR cameras can take timed photos of a vehicle, this allows the system to determine how long a vehicle has used the car park for and to charge them accordingly. This could potentially remove the need for the driver to purchase a parking ticket, as the ANPR system would be able to show how long the vehicle was in the car park.

In addition to ticketless systems, ANPR technology provides 24/7 monitoring in car parks and could lead to software that shows you when spaces are available. This would improve both car park security and traffic management.

What happens to ANPR data?

Although ANPR is incredibly helpful and effective, its use has raised concerns about data protection in the future of security. This is why there are strict guidelines related to the storage and handling of ANPR data by the police and other authorities.

ANPR data is stored securely by the National ANPR Service (NAS). According to the law, all ANPR data must be deleted 12 months after its capture, unless it’s being used in a criminal investigation. Authorised staff will have access to this data for up to 90 days, but this period can be extended to up to one year for major investigations (e.g. counter-terrorism).

If private companies want to access ANPR data, they must make a request to the DVLA and pay a fee of £2.50. To make this request, the company must be a member of the British Parking Association or the International Parking Community. However, private businesses can’t access data from police databases. 

What are the benefits of ANPR?

ANPR technology offers a whole host of benefits for private businesses and government authorities alike. However, due to the cost of installation, many private companies may be hesitant to adopt this technology.

Here’s why installing ANPR cameras on your commercial property is a great business decision:

1. Improved security

The most obvious benefit of ANPR is that it greatly enhances security on your premises. Your ANPR camera will provide 24/7 monitoring, allowing you to record suspicious activity and hand the footage over to the police if necessary. Plus, having visible cameras or signs warning of ANPR technology on the premises can help deter burglars.

2. Efficient access control

With an ANPR system, you can streamline your business’s access control by immediately granting access to vehicles recognised by the ANPR cameras. At the same time, unauthorised vehicles will be rapidly identified and denied access by the system.

3. Automation

Since the ANPR system is entirely automated, your employees won’t need to spend time managing the system or granting access to the premises themselves. This will save a lot of time and money overall through greater efficiency.

4. Accuracy

Since there’s no need for human intervention, you can eliminate the risk of human error. As long as your database of authorised vehicles is accurate, you won’t need to worry about your access control system letting the wrong people in by mistake.

Interested in an ANPR system for your business? Here at Expert Security, we always send over a team of professionals to survey your premises before installation, ensuring that you get the perfect access control system for your business. Get in touch for more information on our ANPR cameras and the installation process.