A Brooklyn man's video showing a series of subway riders tripping on the same step while exiting a station in Sunset Park has caught the attention of the MTA.

Posted online Wednesday, it instantly made its rounds on various blogs and forums. The video, by filmmaker Dean Peterson, opened with a message: "The subway station I use every day has something very peculiar about it... One of the stairs is a fraction of an inch higher than all the others."

In less than 12 hours, "New York City Subway Stairs" had 330,000 views.

Peterson told NBC 4 New York that he started documenting the falls at the 36 Street subway station, served by the D, N and R trains, because the step often tripped him.

"My girlfriend and I would walk up all the time, and we would always trip," he said. "We just thought we were kind of klutzy. But then I kind of noticed that other people were doing it, too."

Peterson's video shows person after person tripping on the seemingly innocuous step in the middle of the staircase. Some catch themselves instantly; others fall straight to their knees.

In one worrying instance, a man carrying a baby jerks forward as his foot catches the offending step. He is able to regain his balance by grabbing on to another step in front of him with his free hand.

The dangerous step, it turns out, is a half-inch higher than the others. Stairway design guidelines call for risers to be a minimum of 6 inches and a maximum of 7 inches, according to MTA spokesman Kevin Ortiz. The allowable variance is 3/8 of an inch.

It's not clear why the step was built that way, but after the video went viral and reporters started calling, the MTA went to work.

Crews went to the station Wednesday to block off the staircase in preparation for repairs. The MTA said Thursday that the work had begun and involves the replacement of the entire stairway.

"The repair cannot be limited to one stair riser; the entire stairway will need to be refurbished," Ortiz said in an email to NBC 4 New York.

There are two additional stairs on the west side of Fourth Avenue that customers can use in the meantime. A notice has been posted alerting customers of the emergency repair in progress.



New York City Subway Stairs from Dean Peterson on Vimeo.

Get the latest from NBC 4 New York anytime, anywhere. Follow us on Twitter, Facebook and Google+. Get our apps here and sign up for email newsletters here. Get breaking news delivered right to your phone -- just text NYBREAKING to 639710. For more info, text HELP. To end, text STOP. Message and data rates may apply.

