FREMONT -- Seven-tenths of a second goes by in the blink of an eye, but it's enough time to dramatically reduce violations at Fremont's most ticketed red-light camera approach and potentially cut in half the city's red-light camera enforcement profit.

At the request of a red-light camera opponent, Caltrans last November studied vehicle speeds approaching the south Fremont intersection of Mission and Mohave boulevards, which is part of a state highway. Based on the evidence collected, Caltrans extended yellow-light times from the minimum-allowed 4.3 seconds to 5 seconds.

The switch likely was made with safety in mind, but the most measurable change thus far has been the sudden 62 percent drop in red-light tickets at the approach, which last year accounted for nearly one in five of all camera-enforced tickets in Fremont.

The sharp drop in tickets has helped reignite a long-running debate over whether the key to safer roads is red-light camera enforcement or slightly longer yellow lights.

"To me, it's pretty clear and convincing evidence that if we were serious about safety, we would look at extending yellow-light times," said Roger Jones, the Fremont resident who requested Caltrans study the intersection.

Caltrans, which oversees traffic signals on two of Fremont's 10 red-light camera approaches, did not respond to requests to discuss its traffic study.

Fremont Traffic Engineer David Huynh said that lengthening a yellow light based on a study of vehicle speeds could improve safety, but that artificially long yellow-light times most likely would lead to longer lines of cars waiting for their light to turn green.

Fremont police defend the camera system, pointing to studies showing that it has reduced collisions.

Also, the city's camera system has not only paid for itself, it has been generating annual profits of more than $300,000 in recent years.

But the longer yellow light at Mission and Mohave could take a large bite out of that profit. During the last seven months, that intersection has dropped from the city's top ticket generator to fifth-highest.

Fremont receives just under $166 for every $476 red-light camera ticket that is paid in full, city officials said.

At Mission and Mohave the number of citations dropped from an average of 185 in the three months before the yellow lights were extended to an average of 71 from December through February.

Assuming that the city collects about three-quarters of the ticket revenue, it stands to lose nearly $170,000 over the course of a year.

In Newark, yellow lights at all camera-enforced intersections are set 0.7 seconds longer than state minimums. The city didn't set yellows longer to promote safety, but to ensure the system was consistent and that tickets would hold up in court, Newark police Chief Jim Leal said.

Subsequent traffic studies have shown no safety problems from the longer yellow lights, he said.

Fremont sets yellow lights throughout the city between 0.1 and 0.4 seconds above minimums.

Contact Matthew Artz at 510-353-7002. For more Fremont news, go to wwwibabuzz.com/tricitybeat.