Editing Traffic enforcement camera (section)

===Accuracy===
In December 2012, Speed Camera Contractor Xerox Corporation admitted that cameras they had deployed in Baltimore city were producing erroneous speed readings and that 1 out of every 20 citations issued at some locations were due to errors.<ref>{{cite web|url=http://articles.baltimoresun.com/2012-12-14/news/bs-md-speed-camera-error-rate-20121214_1_camera-tickets-camera-contractor-xerox-state|title=Some Baltimore speed cameras have 5% error rate, Xerox says|website=Tribunedigital-baltimoresun|access-date=2016-06-30|url-status=dead|archive-url=http://archive.wikiwix.com/cache/20160701020450/http://articles.baltimoresun.com/2012-12-14/news/bs-md-speed-camera-error-rate-20121214_1_camera-tickets-camera-contractor-xerox-state|archive-date=2016-07-01}}</ref> The erroneous citations included at least one issued to a completely stationary car, a fact revealed by a recorded video of the alleged violation.<ref>{{cite web|url=http://articles.baltimoresun.com/2012-12-12/news/bs-md-speed-camera-stopped-car-20121212_1_potential-citation-xerox-state-camera-ticket|title=Baltimore issued speed camera ticket to car stopped at red light|website=Tribunedigital-baltimoresun|access-date=2016-06-30|url-status=dead|archive-url=https://web.archive.org/web/20130127174722/http://articles.baltimoresun.com/2012-12-12/news/bs-md-speed-camera-stopped-car-20121212_1_potential-citation-xerox-state-camera-ticket|archive-date=2013-01-27}}</ref>

In the city of [[Fort Dodge, Iowa]], speed camera contractor Redspeed discovered a location where drivers of school buses, big panel trucks, and similar vehicles have been clocked speeding by the city's mobile speed camera and radar unit even though they were obeying the 25&nbsp;mph speed limit. The errors were due to what was described as an "electromagnetic anomaly".<ref>{{cite web|url=http://www.messengernews.net/page/content.detail/id/545083/|title=Chief cites 'Bermuda Triangle'|website=Messengernews.net|access-date=2016-06-30}}</ref>

Where verification photos are recorded on a time sequence, allowing the calculation of actual speed, these have been used to challenge the accuracy of speed cameras in court. Motorists in [[Prince George's County]], Maryland, have successfully challenged tickets from Optotraffic speed cameras where they were incorrectly ticketed at over 15&nbsp;mph over the limit.<ref name="opto">{{cite news|url=http://www.washingtontimes.com/news/2011/apr/20/business-owner-casts-reasonable-doubt-on-accuracy-/?page=all#pagebreak|title=Business owner casts reasonable doubt on accuracy of speed cameras|author=David Hill|newspaper=The Washington Times|url-status=live|archive-url=https://web.archive.org/web/20110425034639/http://www.washingtontimes.com/news/2011/apr/20/business-owner-casts-reasonable-doubt-on-accuracy-/?page=all#pagebreak|archive-date=2011-04-25}}</ref> However, Prince George County no longer allows time-distance calculations as a defense in cases where "the equipment was calibrated and validated, or is self calibrating".<ref>{{cite web|title=Maryland: Innocence Not a Defense to Speed Camera Citations|url=http://www.thenewspaper.com/news/36/3645.asp|publisher=the newspaper.com|access-date=19 January 2014|url-status=live|archive-url=https://web.archive.org/web/20140202113804/http://www.thenewspaper.com/news/36/3645.asp|archive-date=2 February 2014}}</ref> The National Highway Traffic Safety Administration standards for "across the road radar" state that "If the ATR device is to be considered for unattended operation, the manufacturer shall provide a secondary method for verifying that the evidential recorded image properly identifies the target vehicle and reflects this vehicle's true speed, as described in §5.18.2. This may be accomplished by means of a second, appropriately delayed image showing the target vehicle crossing a specified reference line."<ref name="NHTSA">{{cite web|url=http://www.nhtsa.gov/DOT/NHTSA/Traffic%20Injury%20Control/Articles/Associated%20Files/810845.pdf|title=Speed-Measuring Device Performance Specifications:Across-the-Road Radar Module|website=NHTSA.gov|access-date=2016-06-30|url-status=live|archive-url=https://web.archive.org/web/20160319042701/http://www.nhtsa.gov/DOT/NHTSA/Traffic%20Injury%20Control/Articles/Associated%20Files/810845.pdf|archive-date=2016-03-19}}</ref>

In January 2011 Edmonton, Alberta cancelled all 100,000 "Speed On Green" tickets issued in the previous 14 months due to concerns about camera reliability.<ref>{{cite web|url=http://www.edmonton.ca/city_government/news/intersection-safety-camera-spe.aspx |title=Intersection Safety Camera Speeding Tickets Cancelled :: City of Edmonton |access-date=February 8, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20130926170200/http://www.edmonton.ca/city_government/news/intersection-safety-camera-spe.aspx |archive-date=September 26, 2013 }}</ref><ref>{{cite web|url=http://www.edmontonpolice.ca/TrafficVehicles/IntersectionSafetyCameras/ISCCancellations.aspx |title=Intersection Safety Camera Ticket Cancellations |access-date=February 8, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20111105094905/http://www.edmontonpolice.ca/TrafficVehicles/IntersectionSafetyCameras/ISCCancellations.aspx |archive-date=November 5, 2011 }}</ref>