Citation

Gregg M, MacWillie M, Ogura G. ITE J. 2010; 80(5): 34-38.

Copyright

(Copyright © 2010, Institute of Transportation Engineers)

DOI

unavailable

PMID

unavailable

Abstract

Automated enforcement increasingly is being used for enforcing speed limits, toll collection and red light compliance. However, countermeasure devices are being used to render automated enforcement cameras useless. This article discusses a field test that was conducted in Los Angeles to test the effectiveness of these countermeasures. Most of the countermeasures are designed to exploit the strobe or flash of the cameras. The intent is to increase the reflectivity of the license plates, thereby overexposing the photograph and making the plate image unreadable. These products are illegal in California. The field tests evaluated three products: a brand-name photo spray, a generic lacquer spray and a license plate shield. Results showed that the countermeasures occasionally (but not often) have a minor effect on plate legibility, but that this effect is usually not enough to make a license plate image unreadable. The license plate shield often increased readability. The cameras were activated 160 times, with each activation capturing a front and rear plate image. In none of these incidents were both front and rear plates unreadable. Plate legibility was much more affected by sun glare, flash intensity and the type of automated enforcement system used than the tested countermeasures.