According to a state memorandum, problems with Tennessee’s new license plates and automatic plate readers have less to do with plate design than with reader technology.
Last month, the Tennessee Department of Revenue was notified that several automatic license plate reading systems were having trouble reading the new blue and white plates. The state began distributing the plates this year.
The note published on Wednesday highlighted the differences between five plate reading systems. Two were able to successfully read the new plates each time. The other three could only read a third or less of the samples.
The readers, adopted by many law enforcement agencies across Tennessee, scan plates in a database to search for cars linked to crimes. Last month, the Metro Nashville Council passed legislation allowing police to start a pilot program using the readers.
After issues with the plates were brought to the attention of state officials, the Tennessee Highway Patrol tested multiple plate samples on five plate-reading systems used in the Nashville area, according to the memo.
The systems seem to work well during the day, but at night the infrared illumination can struggle to show the contrast between the reflective and non-reflective parts of the plate.
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“Tennessee standard license plates are produced by printing a blue background on a reflective white sheet,” the memo reads. “In theory, the printed background would reduce the reflectivity of the white media to create adequate contrast to be read by LPR systems. The contrast provided by this inverted plate design is not ideal for some models.”
Last month, highway patrol officers tested 18 plates with different paint formulas against five locally used systems. The memorandum did not identify the systems by name or specify which agencies used them.
The first two systems successfully read all 18 plates. The third read only four, the fourth successfully read one, and the fifth could not read any.
About two weeks later, the patrollers tested five specialty plates against four of the same systems in the previous test. One system was down at the time of the test.
The first two systems were again able to read all five plates. The remaining systems were unable to read any of them, according to the memorandum.
“There are different plate designs across the country, and these companies are responsible for adjusting or updating their equipment and software to ensure that they can provide acceptable services,” the memo reads. “Their responsibility is to ensure that their equipment can read license plates produced to legal standards.”
The Department of Revenue said it would send a copy of the new plates to any plate reader company upon request to help recalibrate the technology if needed.
Contact Tennessean reporter Kirsten Fiscus at 615-259-8229 or [email protected] Follow her on Twitter @KDFiscus.