The mom of a teenager who died “subway surfing” in February spoke out Friday after another teen died performing the same dangerous stunt, saying the MTA is “full of s–t” because it has known about the tragedies for decades but done nothing to stop them.

Norma Nazario, whose son Zackery died after he hit his head on top of a J train as it rolled across the Williamsburg Bridge said the MTA needs to do more, such as locking the access doors at the ends of cars.

“The doors need to be locked, unless it’s an emergency – then they can open,” Nazario told The Post, adding that the agency should also install cameras and sensors so it can detect people straying from the cabin. “If they had done something 15 years ago … my son would still be here.”

“The MTA is full of s–t,” the bereaved mother continued. “The MTA has failed us. And it continues to fail parents. But they’re not going to do anything – it’s all talk and talk and talk. And the carnage continues.”

That carnage claimed another life yesterday, when 14-year-old Brian Crespo and his unidentified friend were thrown from a Manhattan-bound L train in Brooklyn near the Broadway Junction Station at about 1:45 p.m.

Cops found the boys under the train near near the Bushwick Avenue and Aberdeen Street station. Both were suffering from severe injuries.

Crespo, a high school student in Ridgewood, Queens, died at the scene. His pal was rushed to the Cohen Children’s Medical Center, where he was in stable condition.

“This incident is tragic on so many levels and our hearts and prayers go out to [Crespo’s family],” NYPD Chief of Transit Michael Kemper told reporters at a Thursday press briefing with Mayor Eric Adams. “We urge anyone even thinking of subway surfing, don’t do it.”

“Subway surfing kills,” the mayor added. “This is a tragedy.”

The MTA leaves doors unlocked on train cars that measure 60 feet or shorter in case of an emergency. This includes the L train – where Crespo died – and the J train – where Zackery Nazario died.

Doors on other trains – such as the larger cars that run on the A, B, C, D, N, Q and W lines – are locked because they wouldn’t allow for a safe emergency exit, according to the agency. But train crews can remotely unlock the doors if need be.

Mayor Adams blamed social media for fueling the craze – as he said some New York subway surfing videos posted to sites like TikTok had tens of millions of views.

“They’re being exposed to dangerous and disturbing findings and radicalizing content,” the mayor said, adding that TikTok should ban the clips.

Adams said the number of people subway surfing skyrocketed by 366% between 2021 and 2022.

In February, there were 52 reports of people riding outside subway cars in the city – six less than were reported the month before, according to the most recent MTA statistics.

There have also been the casualties.

In March, a 14-year-old boy died after he fell between subway cars in the Bronx while riding on top of a 5 train.

And a month earlier, Nazario’s son died on the Williamsburg Bridge.

Nazario agreed with the mayor’s idea of banning the clips from social media, which she said encourages teens to stroll into extraordinary danger. And she wants the city to make laws that might help save young daredevils from themselves.

“Something needs to be done,” Nazario said. “I wish I could just push a button and get this finished.”