Photo: PIPS Technology
It's hard to believe that automated license plate recognition systems (ALPR) have been around for less than a decade. These wonders of technology decipher the letters and numbers on plates from every state and match them against hotlists selected by a law enforcement agency. With the ability to scan around 1,800 plates per minute, if a plate that's in a system's hotlist passes by, an ALPR system is going to detect it.
It's now common for even a small agency to have at least one car equipped with ALPR to automatically alert when it gets a match. But both mobile and fixed camera systems are gaining traction with all types of law enforcement agencies. That's because they can be used for different targeted strategies and all without an officer having to manually key in the license plates or call them in to dispatch.
Mobile v. Fixed
When it comes down to it, license plate recognition systems serve the same basic function, whether moving in a car or stationary on a pole or building. But their positioning determines how they can be used.
"One of the major benefits [of a mobile system is] Instead of being fixed at an intersection or along an interstate, officers can choose where to collect license plate data and collect thousands of plates an hour," says Bryan Sturgill of PIPS Technology. However, stationary cameras can be useful for long-term projects that don't require constant manual monitoring. "A fixed system doesn't have to be installed or assigned in a specific vehicle," explains Sturgill. "It can be strategically located in a high-crime area or something of that nature."
These different benefits come into play when determining how to utilize license plate recognition. No longer just for identifying stolen cars, mobile and stationary cameras play important roles in maintaining order and solving major crimes.
"A single camera mobile ALPR system can be used for anything from essentially revenue collection to drug enforcement, stolen cars, and historical data collection," says Dave Carson, technical services manager for CitySync. "With fixed LPR, it keeps a brief record of who passed by, and if an event happened last night, you can see who drove in during that time."
Clearly, a solution that incorporates both mobile and fixed cameras yields the most effective results in investigating crimes, and allows for the most flexibility in overall application. But the ideal is not always possible, at least at the outset. "Once they get a mobile system or two, they tend to start asking about fixed cameras," Carson adds.
One of the major benefits of ALPR systems is that officers can immediately apprehend offenders when a certain license plate is recognized. This is made possible by the use of hotlists.
A police department can determine which lists it wants to maintain to check plates against. When a match is found in any database, an alert will in most cases visually and audibly notify an officer or other person monitoring the system.
NCIC is the most recognized such hotlist, but it's by no means the only one that can be used. There are hotlists of license plates associated with arrest warrants, sex offenders, and even people who haven't paid their taxes in some states. In fact, databases can be specially customized for how an agency wants to use its ALPR system. "They can create their own local databases so they can look for local subjects or perpetrators that may not be in a national database," says Sturgill of PIPS Technology.
ALPR can also be used for geo-fencing of sex offenders. In this case, an alert would only sound if the license plate of a registered sex offender were detected within 500 yards of a school or playground. If the license plate were detected in an area that is legally allowable under the law, no alert would pop up.