MODESTO, CA—Speaking in his downtown office, Mayor Garrad Marsh told Ars that he has lots of questions for Redflex, one of the largest red light camera (RLC) operators in the United States.

Years ago, when the Australian company’s cameras first came to this Central California agricultural city of 200,000 people, Marsh was a city council member who was generally positive on the idea of using automated cameras to catch drivers dangerously zooming through intersections at high speed. “Now, I’m not sure... to almost negative,” he said.

Modesto features an active downtown area replete with shops, city offices, taco trucks, and a transit center, but the city has expanded significantly to the north and east. That’s where Modesto seems to be miles after miles of flat, single-family homes, strip malls, and big box retailers. Drivers regularly blow through red lights at intersections on these long, straight streets.

In June 2004, Modesto’s city council noted (PDF) that the city had 313 intersection collisions (with 170 injuries) “directly attributable to red light running” in the previous year. The council unanimously approved installing cameras at “up to 10” intersections as part of a five-year contract with Redflex. The city believed at the time that “the implementation of red light photo enforcement will significantly reduce the number of red light violations in the City of Modesto” and that the city would have “another valuable traffic calming tool to improve community and pedestrian safety.”

Besides safety, an added benefit of the Redflex system was its "cost neutral" basis, meaning the city would never pay Redflex anything beyond a percentage of the fines generated by the camera system. This is a common approach to many red light camera contracts, designed to make the system easy for cities to approve.

Marsh voted for the resolution at the time, and he said that the goal was never for the city to make more money—a common argument against red light cameras. “It's difficult for a cop to give a red light ticket [under normal circumstances,]” Marsh told me. "The reason is that it’s, ‘He said, she said.’ There's no proof that I entered before it turned red. It's just difficult. So [with the red light cameras] we might make a little money on it, but that was not one of the decision points for anybody. We could have greater safety and not have to utilize cops sitting on an intersection to figure out if someone ran a red light.”

But doubts crept in. A year after supporting the Redflex system, Marsh wanted to see the actual camera setups. He drove out near Highway 99 at Sisk Road in the northwest corner of town, close to the Vintage Faire shopping mall. What he saw surprised him. The red light camera at the intersection was "set up to only monitor the lane coming off of Highway 99 onto Sisk, going north,” Marsh said. “That was the only monitored lane—the turn lane is not the T-bone situation,” he said, referring to a dangerous scenario where one high-speed car plows into another at a near-right angle.

“You're not blowing through a red light the way that a truly dangerous situation would be. That looks like they've picked the one where they can make money off of it. That was what got me thinking.”

Some of his doubts were allayed at a meeting with Redflex representatives, who showed off footage of a driver at another Modesto intersection who clearly made no attempt at slowing down as he blew through a red light. “It was clearly the type of ticket you would want to give, the type that I voted for, that would cause a serious possibly fatal accident—that kind of kept me at bay for a while,” Marsh said. “It was really a dynamic and impressive piece of film.”

But he was still troubled by the focus on turn lanes and continued to look into the implementation details of the Redflex setup. Marsh found that "most of the tickets [we issue from red light cameras] are right-hand turn. It's illegal, it's dangerous, but it's not the 'fatal accident' type of turn.”

This was a pattern. The cameras in Modesto are mounted across four intersections, but they are only set up to capture six precise situations. As the Modesto Bee noted in October 2013, the cameras watch drivers who are:

• Turning left from eastbound Standiford Avenue onto northbound Sisk Road

• Turning left from eastbound Briggsmore Avenue onto northbound Prescott Road

• Traveling north on Coffee Road through Sylvan Avenue or turning east onto Sylvan from northbound Coffee

• Traveling north on Oakdale Road through Briggsmore or turning east onto Briggsmore from northbound Oakdale

In short, just two out of the six deployments are even designed to capture the most dangerous scenario worrying citizens and city officials alike: cars blasting straight through a red light at high speed.

“We're collecting $1 million from our residents and sending most of it to Arizona,” Marsh said, referring to Redflex’s American subsidiary located in the Grand Canyon State. “I'm going: are we really making our intersections safer? If it was $1 million and it all stayed in Modesto, I might not be so pessimistic or cynical. And if it proves to truly produce safer intersections without having to utilize personnel to be there that aren't out there catching bad guys or patrolling. I'm not guaranteeing that I'll vote against it or change, but I am quite concerned that it's not what we bought, and it doesn't do good for our local economy.”

According to the Modesto Police Department, the mayor's $1 million reference describes the total amount collected in fines across three years. Of that money, the city keeps only ten percent (in this case, $110,000)—the rest goes to Redflex and to pay the part-time salary of one Modesto police officer who helps manage the system.

Rajiv Shah, a professor at the University of Illinois at Chicago who studied red light cameras in Chicago in 2010, said that Marsh's observations are spot-on.

“A significant portion of the red light cameras—maybe 70 or 80 percent—are for rolling right turns,” Shah told Ars. “When you think of RLC, they're for people blowing through the intersection, which don't have nearly the same kind of chance for accident or injury. A lot of people feel like it's really unfair, doing the things like the right turns.

“There’s nothing wrong with using technology to improve traffic safety. What's wrong with RLC is that the emphasis became on revenue instead of traffic safety early on, and that led to decisions on business models and locations and how they set up fines, warnings, education. That left a bad taste in people's mouths,” he added.