A growing body of evidence shows red-light cameras on Long Island reduce auto accidents where they operate, including those that cause injuries. They also bring in tens of millions of dollars in revenue, but if the counties get too greedy, drivers could revolt.

In 2015, auto accidents that caused injuries at red-light-camera intersections in Nassau County declined 43 percent compared with the 12-month period before each was installed. And total crashes at those intersections were down 31 percent. In Suffolk County, total crashes have fallen 6 percent annually at intersections with cameras since the program began in 2009, and crashes with injuries are down 5 percent a year.

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That means the red-light-camera programs are worth preserving. But both Nassau and Suffolk must use the cameras and the data to make the roads even safer. At intersections that haven’t improved or have gotten worse, traffic engineers need to figure out why and address the issues. And they particularly need to find answers to problems that have increased, such as rear-end collisions in Suffolk County.

Nassau tried to add a new $105 “administrative” fee to traffic tickets last year before settling for a bump of $55 in the face of voter outrage. Suffolk was set to double its $55 “administrative” fee last week until similar anger derailed the plan. Both moves were clearly intended to deal with broad budget woes, not administrative costs.

Red-light cameras are effective safety tools. But if the counties use them to raise money, the voters are going to raise fierce objections, and the cameras could come down. And that could cost lives. — The editorial board