By on August 30, 2010

The Institute of Transportation Engineers Journal published in May the results of an extensive Los Angeles, California Police Department evaluation of the effectiveness of license plate covers and sprays designed to defeat automated ticketing machines. The results showed that the popular countermeasures did not work well under actual field conditions using the red light cameras operated in the city by Nestor Traffic Systems (the firm has since gone bankrupt and American Traffic Solutions now runs the program).

Los Angeles has 32 intersections with cameras that use both video and flash photography for issuing near $500 tickets to the owners of vehicles photographed turning right on red or entering an intersection a split second after the light turns red. Photos are taken both of the driver and the vehicle’s rear license plate. The test looked at Photoblocker high-gloss spray that claims to reflect the flash and cause the photograph to overexpose, as well as a convex license plate cover also designed to reflect the flash. These devices were installed on three 2007 Ford Crown Victorias belonging to the Los Angeles Police Department, with a fourth serving as a control vehicle. The cars were then run through the intersection of Sherman Way and Louise Avenue which were shut down to traffic for the test.

With the signals set to display a constant red light, the cars were run through a total of 160 times in straight-through and turn lanes at night and during the day heading both westbound and eastbound. Night time results were conclusive.

“The countermeasures had no effect on plate legibility under dark conditions, with the exception of V-2 (license plate shield), which occasionally caused a slight increase in front-plate legibility in half of the images,” the study found. “All rear plate images were clearly legible, with no significant difference between the test plate images and the control plate image. A citation could have been issued in all cases.”

Results from testing at 8am to 9am, however, were less clear with the sun low on the horizon causing a significant amount of glare.

“The countermeasures had very little effect on the rear-plate vehicles, with the exception of the license plate shield, which caused a 38 percent reduction in plate legibility when combined with sun glare,” the study found. “The rear plates on the westbound vehicles plates experienced more sun glare than any other group in the test. This is most likely because the angle of the plate in relation to the sun reflected the glare more directly into the camera.”

Photoblocker and a generic equivalent decreased legibility in 10 and 20 percent of the cases compared to half of images rendered unreadable with the cover. Headed eastbound, away from the sun, the images were all high-quality regardless of the countermeasures used.

“The overall average image quality scores reveal that the brand-name photo spray and generic lacquer spray both decrease image quality by about five percent, with the brand-name spray having a slight advantage,” the study concluded. “The license plate shield shows a five percent overall increase in image quality, which means that when all eight categories are considered equally, this countermeasure had the opposite of the intended effect.”

In March 2007, the Discovery Channel’s MythBusters television program came to a similar conclusion after testing several types of plate covers against cameras operated by ATS. In June 2008, Pennsylvania’s attorney general banned Photoblocker from the state because of the questionable claims made on its website (view ruling).


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12 Comments on “LAPD Test Finds License Plate Covers, Sprays Ineffective...”

  • avatar

    A more effective solution:

    1. Register your car in a company name
    2. Remove the front plate
    3. Wear a burka.


  • avatar
    John Horner

    I can hardly wait for the class action lawsuit to get in front of a judge :).

    People are, by and large, suckers. Miracle spark plugs, miracle “tornado intake devices” and miracle motor oils have been joined on the shelves by miracle no-get-a-ticket trinkets. Meanwhile, actually obeying traffic laws is the fix which actually works most of the time.

    • 0 avatar

      As long as obeying the traffic laws is a do-able thing….
      shortened yellow-light times….
      not very visible traffic signs….
      40 mph zones on the interstate in the middle of nowhere…

  • avatar

    Where the testing regarding the efficacy of the warning upon the front windshield sun blockers warning the user to “remove before driving”?

  • avatar

    I think the Mythbusters came to the same conclusion.

    • 0 avatar
      The Walking Eye

      Indeed they did. They did tests on speed cameras and nothing could outrun it, and IIRC they used a rocket car that still couldn’t.

      I’m sure the people of California are happy their police department wasted money for this study when they could have watched an episode of Mythbusters or consulted literature instead.

  • avatar

    I suppose mud would still work, and it’s far less expensive. Of course, having a fairly clean car with muddy plates will probably guarantee real life officers will decide to speak with you about it, nor would they believe you just took your BMW Z4 offroading.

    • 0 avatar

      Snow works during the winter. My brother had a friend with expired plates and everyday he would back into a snowbank just to fool the cops even though that alone is reason for a police officer to pull you over up here.

  • avatar
    M 1

    States, counties, and cities are facing bankruptcy, and they see fit to shut down an intersection to waste a day running tests of something that is already known to be ineffective.


  • avatar

    Solution to the license plate dilemma with both speed cameras and redlight cameras – get a motorcycle and wear a full sized helmet with a mirrored or tinted faceshield to prevent facial identification. Then, arrange a fannypack or a tailbag to fall over the rear plate, thus obscuring the plate….note – running redlights with a motorcycle is extremely hazardous!

    • 0 avatar
      Brian P

      Locally, we have a major toll road that uses photo identification of the license plates to send you a bill. The cameras are overhead pointing down at an angle towards the rear plate – speed cameras and red-light cameras are usually at the side of the road at a different angle, but still …

      On some trucks and SUV’s, strategic positioning of the license plate, tailgate, spare tire carriers, etc can sometimes block the toll cameras from viewing them.

      On a motorcycle, a co-operative passenger can be helpful, too.

      Or just do a wheelie through the camera station; just make sure the cops aren’t watching.

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