An eight-mile stretch of Brooklyn's Atlantic Avenue will be the first major corridor to go on a speed diet as part of Mayor Bill de Blasio's Vision Zero traffic fatality prevention plan, the Department of Transportation announced Wednesday.

The city will post new signs lowering the 30 mph limit to 25 mph by the end of month on the major thoroughfare where motorists often drive as if they're on a highway.

This will be the first of 25 slow zones that will be added throughout the city on so-called arterial streets, which are wide roads that transportation officials say encourages speeding.

"Crashes on these roads tend to be more deadly and you can see why," DOT Commissioner Polly Trottenberg said as cars sped down a section of Atlantic Avenue in Prospect Heights. "Arterials is the No. 1 issue we hear about."

Between 2008 and 2012, there were 25 fatalities, including 13 pedestrian deaths, on the corridor according to the DOT.

The 7.6-mile slow zone will cover Atlantic Avenue from the Brooklyn waterfront into Woodhaven, Queens, at 76th Street. To encourage driving within the new speed limit, the timing of traffic lights will be changed.

The DOT is also considering a build out of the median strip for pedestrians to shorten the crossing distance.

The NYPD will also have local precincts step up enforcement of speeding, failing to yield to pedestrians, cellphone use, illegal turns and other types of dangerous driving.

NYPD Transportation Chief Thomas Chan stressed city agencies' outreach to drivers about Vision Zero, along with stepping up police action.

The DOT would also like to add speed cameras to Atlantic Avenue, Trottenberg said, noting that Albany has "some pretty tight restrictions" on where they can be installed.

The city has had five speed cameras in operation since mid-January, netting 14,500 tickets. There are plans to install 20 cameras over the next few months as the city continues to push Albany to allow for more.

"There's no question when you look at areas where you put in speed cameras, you do see that people really slow down. It's been proven effective all over the world," Trottenberg said.