Protective screen doors are coming to platforms at three subway stations as part of a new pilot program to keep straphangers off the tracks, Metropolitan Transportation Authority Chairman Janno Lieber said Wednesday.

The MTA had already discussed installing protective barriers on platforms in the past, but determined it was too costly and logistically challenging for most subway stations. But after several high-profile incidents in recent years where riders were shoved onto the tracks, including the January death of Michelle Go in Times Square, the agency said it would revisit the issue.

Speaking on NY1, Lieber said the agency would begin by installing the protective platform doors at the Times Square 7 train, the Third Avenue L train and Sutphin Boulevard-Archer Avenue E train stop at the JFK AirTrain connection. The R train platform, where Go, 40, was shoved to her death, was not included in the pilot.

A 2019 report commissioned by the MTA on how expensive and technically challenging it would be to install platform screen doors at all 472 stations found that only 128 stations could physically accommodate protective doors. It estimated the total cost for the program at $7 billion.

But for now, three stations is better than zero, Manhattan Borough President Mark Levine said in a statement.

“This pilot program is an important first step toward making our subway system a more resilient and safe place for commuting New Yorkers," Levine said. "It will not only help stop future tragedies like the Michelle Go murder, but also prevent other incidents like people falling on the tracks, suicide attempts and track fires, which are some of the main causes of subway delays."

Yonah Freemark, senior research associate at the Urban Institute, said in a statement the three-station rollout was underwhelming compared to similar projects in other parts of the world.

“Paris installed platform doors on the entirety of their Lines 1 and 4—all the stations at the same time," he said. "But three stations is better than no stations. And if the pilot is effective, I am hopeful it would mean rapid progress in installing doors throughout other parts of the system."

The MTA has also reported a recent rise in unauthorized people walking on the tracks. In December, there were 14 incidents that delayed trains due to people on the tracks, including one fatality on the Manhattan Bridge that suspended service across four lines. Lieber said the pilot included plans to bring those numbers down.

“We're also going to be piloting new technologies to detect track incursion using thermal technology, using laser technology, so we can know quicker when people get on the tracks and hopefully, interdict that kind of behavior,” Lieber said.

The city also set its sights on improving what goes on inside the trains as well. The agency, in coordination with the NYPD, mental health and homeless services, launched the Subway Safety Plan earlier this week to address the ongoing issues of homelessness in the subway system and a rise in assaults.

“While we're glad platform doors are being tested, we don't believe this is the answer system-wide, as it would mean platform reconstruction, likely temporary closing of stations, and other issues including rolling stock alignment,” said Kara Gurl, research and communications associate with the Permanent Citizens Advisory Committee to the MTA, in a statement. “Platform doors are one answer to a problem that has many sides, and the MTA needs to use every tool available to keep riders safe. Track intrusion detection software will also help.”

Platform screen doors are used around the world, and systems that use them report less trash on the tracks and fewer deaths related to people falling on the tracks. The MTA had planned to pilot platform screen doors in 2017 as part of the L train tunnel repair project, when it was originally a 15-month endeavor. But that pilot was canceled when former Gov. Andrew Cuomo stepped in and restructured the plans.