The city of Scottsdale, Arizona agreed to cancel speed camera fines issued to 589 innocent motorists. Between December 7 and January 4, a broken piezo sensor embedded in the pavement caused speed estimates to read high at the Shea Boulevard camera located between 120th and 124th Streets.

An official with American Traffic Solutions (ATS), the vendor that operates the program, confirmed in an email that the sensor was freshly installed at the location last year. The site was approved in May as part of a deal that allowed ATS to snatch away the Scottsdale ticketing contract from its Australian rival Redflex Traffic Systems. The official stressed that having sensors go bad is "unusual" and that steps would be taken to ensure the same problem is not repeated.

In July, radar-based warning signs in Chandler displayed wildly inaccurate speed readings to passing motorists. In Scottsdale, a Redflex sensor accused a man of driving 147 MPH in a rented Hyundai Sonata in May 2006, even though the vehicle had a measured top speed of just 137 MPH. Around the same time, another black man had been given a white man's speeding ticket. In 2005, the city was forced to refund a total of 1964 tickets after a mobile speed camera van operator for Redflex made a change in the software that removed date, time and speed information from every alleged violation.

The Shea Boulevard photo radar tickets would have been worth between $100,000 and $125,000 in revenue, but the 36 who have already paid will receive a refund and all others will receive a notice that the fine has been canceled. The piezo sensor has already been replaced and the ticketing resumed earlier this month.