Red light cameras are slowly coming back to San Francisco city streets.

The previous generation of red light cameras — old, analog devices that used, get this, actual film — were deteriorating over time, and finally taken offline completely in January. Since then, the San Francisco Municipal Transportation Authority has been installing new, digital cameras as part of a $2.5 million upgrade project.

Erica Kato, an SFMTA spokesperson, said that as this week, four of the new cameras had been operating for more than 30 days, during which they had generated 670 citations.

Five additional cameras came online within the last month. By the end of 2019, a total of 19 are expected to be up and running (although one, at Van Ness and Broadway, is part of the Van Ness Bus Rapid Transit project and won’t see use until the BRT is completed).

Each camera covers only one approach to an intersection, meaning it would take several cameras to have full enforcement at a single intersection. Those 19 cameras are spread out across 13 intersections.

The construction costs for installing a camera include the camera poles, flash units, conduits, and more. The $2.5 million spread across 19 approaches comes out to approximately $132,000 per camera.

“We’ve had a program that’s been relatively successful in that it’s maintained public support, which is an important thing to have for a camera enforcement program,” Ricardo Olea, a city traffic engineer, told SFMTA directors at a Policy and Governance Committee meeting Tuesday morning. Red light cameras in other cities have faced some technical and legal challenges, prompting some cities to abandon their programs.

“Even in California, there’s been issues with feelings from the public that the systems are sometimes installed to make money,” Olea said. “We want to make sure the public is aware that in San Francisco, the main goal of the red light program is to improve safety.”

Olea said there’s also sometimes public confusion about what does and doesn’t constitute a red light violation. In California, citations for running lights are only issued to vehicles entering an intersection when the light is already red.

“So, vehicles that are entering on the yellow, and are still in the intersection on the yellow, are still legal — and the vehicle code requires those people to just clear out,” he said.

SFMTA has even added a grace period, giving drivers another 0.3 seconds after the light has turned red to enter the intersection before issuing a citation.

That’s not the only timing tweak SFMTA has implemented. Traffic lights in the city are programmed with yellow times longer than the state-mandated minimums to give pedestrians longer to clear an intersection. Intersections also have an “all red clearance phase” — that one, or two second pause after a light turns red before opposing traffic gets a green.

“When I started working for the city a long time ago, we didn’t have that as a tool,” Olea said. “But now we do it based on a formula, so the wider the street, the longer the pause.”

Bicycle and pedestrian advocacy groups said they were generally pleased with the return of red light cameras to San Francisco, but were eager for more than just 19 of them. At its peak, under the old analog system, there were some 47 cameras across the city.

“We know red light running is one of the most dangerous driving behaviors, and most likely to lead to a traffic crash or hurt people,” said Marta Lindsey, communications director for Walk SF. “It’s a wild west out there. No one is thinking there is any enforcement of any dangerous driving behavior, so it’s just rampant.”

Olea said SFMTA has started the process of identifying another $2.5 million to expand the program next year.