Drivers accustomed to accelerating when they find a rare patch of congestion-free asphalt in San Francisco may want to consider hitting the brakes. Beginning Saturday, police will start a yearlong crackdown on speeders across the city.

The enforcement campaign, part of the Vision Zero effort to eliminate traffic deaths by 2024, will not only boost enforcement on a dozen of the city’s most dangerous corridors that are already frequented by traffic cops, but bring stiff enforcement to at least 14 more streets where speeding is common.

Officials with the Municipal Transportation Agency, the Police Department, the Department of Public Health and the Vision Zero campaign announced the $2 million effort Thursday at a news conference in the South of Market, one of the deadliest neighborhoods for traffic collisions.

Speeding is a leading cause of crashes that kill pedestrians and bicyclists, the officials said, and the Safe Speeds campaign aims to slow drivers down. Natalie Burdick, outreach director for Walk San Francis-co, an advocacy group for pedestrians, said speeding is most dangerous — and common — in busy neighborhoods like the Tenderloin, Chinatown and SoMa.

“In places like this, where people work, live, shop, where children go to school, where they play, it’s simply not OK to go faster than the speed limit,” she said.

As speeds increase, she said, so does the peril of collisions.

“We know that if 10 people are hit by a car going 40 mph, 9 of those 10 will die at that speed,” she said. “We also know that if 10 people are hit by a car going just 20 mph, 9 of those 10 will survive.”

Capt. Tim Oberzier, who oversees traffic for the Police Department, said the department will add 132 hours a week of enforcement, focused on speeding, for the next year. All 10 district stations will participate in the push, he said, as well as the traffic division. Regular traffic enforcement will continue.

Officers will be outfitted with new lidar speed detectors, which are similar to radar guns but use more reliable laser technology. Using money from a federal grant, the MTA purchased 32 lidar devices for the program, said John Knox White, an agency program manager.

The MTA will also use the money to pay for overtime and campaigns that alert drivers to the crackdown and urge them to slow down.

Oberzier said police will focus on 12 primary enforcement corridors, which include Howard Street from the Embarcadero to South Van Ness Avenue; westbound Pine Street between Jones Street and Presidio Avenue; Leavenworth Street between California and McAllister streets; and Sunset Boulevard between Lake Merced and Martin Luther King Jr. Drive.

Another 14 streets scattered all over the city have been identified as secondary enforcement areas, with other known problem areas targeted as well, Oberzier said.

And what constitutes speeding? Any speed over the posted speed limit, he said. Where a speed is not posted, the limit is 25 mph.

The crackdown, said Ed Reiskin, the MTA’s transportation director, is not designed as a way to issue tickets but to slow traffic.

“We want people to slow down and drive safely,” he said. “And the best way to get them to do that is to have a strong presence.”

Michael Cabanatuan is a San Francisco Chronicle staff writer. Email: mcabanatuan@sfchronicle.com Twitter: @ctuan

S.F. crackdown

To see where San Francisco police will focus their enforcement during the yearlong antispeeding campaign, visit the Municipal Transportation Agency website, www.sfmta.com.