speeding tickets were issued by speed cameras.(Compared to 117,767 speeding tickets issued by officers.)Speeding cameras issuedin fines.Vehicle crashes near cameras declinedCrashes with injuries near cameras declined

Officials won’t say where they’ve placed NYC's controversial speed cameras. But based on where and when tickets were issued, about half of them appear to be in fixed locations. The rest are mounted on city vehicles and rove from place to place.

We've mapped approximate locations of speed cameras that have ticketed consistently as recently as January. Inactive sites indicate roving cameras or fixed cameras no longer operating.

According to state law, NYC can put speed cameras anywhere in the city, as long as they're within a quarter-mile of a school. Ticketing data reveal three general types of locations used to position cameras.

Almost half of the city's speed cameras are mobile — mounted on NYPD vehicles, they watch different spots for a day or two. Officials won't say how those spots are picked, though school principals and community groups can make requests. The mobile cameras each issue just a few tickets a day; as a group they issue only 11.5% of all tickets.

This is the kind of location one might expect for a speed camera. They target busy crossings near some of the city's most dangerous boulevards. These cameras are more common than the "speed traps" but they issue far fewer tickets.

Neighbors and commuters decry these cameras as money-making "speed traps," because they catch drivers exiting highways where there is no pedestrian crossing — here, one side is a fence. Transportation officials say it's about safety, not money, and that cameras protect all road users.

Roving cameras are rarely on for more than a couple days and therefore cannot be meaningfully charted.

Built by Jenny Ye, Louise Ma, Alan Palazzolo, Noah Veltman, John Keefe, Kat Aaron and Kio Stark / WNYC Data News Team.

Camera location photos by Dave Gershgorn, Richard Yeh and Stephen Nessen / WNYC.

Speed camera locations deduced from the locations of tickets listed in the NYC Department of Finance dataset of parking violations under violation code 36, "Photo School Zone Speeding Violation." (Photo tickets are, indeed, classified as parking tickets.) Reported locations can be vague, and the mapped locations are our best estimate. In some cases we combined some relatively close locations on the same stretch of road.

We deemed a camera to be "active" if it was operating for more than 10 days in a fixed location in January 2015 up to Jan. 26, 2015 which is the last day of data used. Cameras can be turned off or moved at any time, so all "active" locations are estimates.

By state law, cameras only operate near schools on school days during school hours.

Dollar values were calculated from tickets issued, which are $50 each. That doesn't account for additional fees or tickets that were dismissed or decreased.

Crash statistics calculated from NYPD collision data from September-December in both 2013 and 2014. We counted all collisions within 500 yards of our location estimations for 21 installed cameras.

Information on hand-written speeding tickets calculated from NYPD monthly citywide reports.