What Is an Automated License Plate Reader?
An Automated License Plate Reader (ALPR) is a camera-based technology that captures images of vehicle license plates and converts the plate characters into machine-readable text using optical character recognition (OCR) software. ALPRs can be deployed in several configurations:
- Fixed/stationary units — mounted on poles or traffic signals at fixed locations
- Mobile units — mounted on patrol vehicles, capturing plates while the vehicle is parked or in motion
How the Technology Works
- A camera captures an image of a passing vehicle's license plate, typically along with a photo of the vehicle itself.
- OCR software converts the plate image into an alphanumeric text string.
- The system records the plate number, along with the date, time, and GPS location of the capture.
- This data is automatically checked against one or more law enforcement databases (e.g., stolen vehicle records, wanted persons, Amber/Silver Alerts, outstanding warrants).
- If the system generates a match ("hit"), an alert is sent to an officer for verification and follow-up.
- All captured data — both hits and non-hits — is stored in a database for a defined retention period, per agency policy.
What Data Is Collected
- Each ALPR "read" typically includes:
- License plate number
- Date and time of capture
- GPS location of capture
- Photograph of the vehicle (and sometimes the surrounding area)
ALPRs generally do not capture driver or passenger identity, vehicle occupants' faces, or the interior of a vehicle.
Data collected from an ALPR “read” is not readily accessible by PD personnel. Relevant data is returned only when a search of the data is initiated for an authorized law enforcement purpose and limited to the user who initiated the search.
Common Uses
- Locating stolen vehicles
- Identifying vehicles associated with active warrants
- Supporting Amber Alerts and missing persons cases
- Investigating crimes where a vehicle was involved (e.g., hit-and-run, robbery)
- Locating vehicles linked to court orders, where authorized by law
Data Retention and Access
- Non-hit data is retained for 21 days after which it is automatically purged, unless flagged as part of an active investigation.
- Access to stored ALPR data is limited to VBPD personnel and requires a documented investigative purpose.