It can do much more than read license plates. When matched with a computerized database, a portable power unit, and a satellite- based Global Positioning System, it can perform in hours what would previously take weeks or months - search for stolen vehicles or ones connected to a crime, analyze parking patterns in an eight-story garage, or, as it did last week on Columbus Avenue, find vehicles with five or more unpaid parking tickets that are eligible for the boot.
The type of license plate doesn't matter either, though some of the dirty and cracked backgrounds on 20-year-old green Massachusetts license plates make the machines burp out bad numbers. To counter that, there's always a human ensuring that the image snapped by the machine matches the license plate number it records.
If the cameras match a license plate with the Boston Transportation Department's database of bootable vehicles, an alarm sounds. The license plate number then flashes on the screen. [David Laspada] checks it to make sure the LPR read it correctly, radios it to headquarters for another check ("They may have paid their fine this morning," he said), then radios a trailing pickup truck carrying a small arsenal of yellow "vehicle immobilizers."