These days, it’s common to see cameras mounted at toll booths, traffic lights, and parking lot entrances or exits. Most drivers don’t even notice them, but these cameras are a crucial part of modern ALPR systems. Short for automated license plate readers, ALPRs are high-speed, computer-controlled camera systems. Read on to find out how they work.

Data Captured

The amount of data gathered by an ALPR system will vary depending on its use. All ALPRs capture license plate numbers and add timestamps. In some cases, the cameras may also automatically take pictures of a vehicle’s driver and passengers.

When used by law enforcement agencies, ALPRs are integrated with relevant databases. The data captured by the cameras can be compared with those databases to identify criminals, resolve Amber or Silver alerts, show when someone is breaking a restraining order, and more. Some ALPRs also capture data such as estimated speed, location, and even travel patterns.

When all of the information is put together, ALPR data can create a fuller picture of a vehicle’s use. It can track drivers who visit sensitive places or events such as health centers, gun shops, union halls, centers of religious worship, and protests. Since all vehicles are required to display license plates, there is no way for drivers to hide their information from law enforcement.

Private Uses

Not all of the uses of ALPRs involve tracking drivers or capturing criminals. These camera systems are also available for use by private property owners. However, in this context, the ALPRs capture far fewer data and have a very different intended use.

When used for parking enforcement, ALPRs simply capture the license plate numbers of each vehicle that pulls through a parking lot or garage gate, then compare it to a whitelist of permitted cars. If the license plate number is on the list, the car’s driver is allowed to park there. If it’s not, the ALPR will send out an alert so that the lot or garage owner knows that there is an unauthorized vehicle on the property.

Stationary vs Mobile ALPR Cameras

Most ALPRs are stationary. They can be found at toll booths and traffic lights, on street poles, and in speed enforcement zones. Some stationary ALPR cameras are also attached to moveable trailers that can be towed to political rallies, gun shows, and other sensitive events by the local authorities.

Mobile ALPRs are almost always found on police patrol cars. They allow officers to capture license plate data over the course of their shifts. If a vehicle on the local police’s hotlist appears, the ALPR software will send out an alert. Hotlists often include stolen vehicles, vehicles associated with people who have outstanding warrants, Amber alerts, and Silver alerts.

ALPRs Are a Useful Tool

Automating the process of collecting license plate numbers can be very helpful to law enforcement offices across the country. An ALPR system can collect and store data from hundreds of vehicles in the amount of time that would be required for officers to note down just a few plates by hand. These automated license plate number collection tools also allow license plate data to be stored for later use in historical investigations, making them an invaluable part of many police activities. Private uses are more limited, but ALPRs can also help property owners identify unauthorized vehicles quickly and efficiently.