Metro is promising to install chains between its new 7000 series rail cars after a visually impaired man says he fell through the gap and on to the track.

David Kosub says the long moments he spent trying to climb out were the most terrifying of his life.

It’s a story first reported by Martin Di Caro of WAMU.

Kosub said it happened at the Grosvenor-Strathmore Station on July 29.

Metro said a station manager helped him recover his cane. But there's no surveillance video of him falling to the track.

Kosub said he's been riding Metro for more than a decade and usually uses the sound of the doors opening and a tap or two of his cane to figure out where to climb aboard. All the older trains have chains between the cars, just in case the visually impaired mistake the gap between the cars for the door.

“And when I took a step, I fell straight down into the gap,” says Kosub, who works at NIH.

Instead of chains, some of the new 7000 series cars just have plastic bumpers.

“Stepped off into the void. That's literally what it was like. This very small hole I never thought would have existed between to train cars.”

Kosub said he landed on his feet -- terrified. “This has to have been the most frightening moment of my life.”

He figured he had just moments to get out. “At one point I thought I heard the train start to make noises to move.”

Grosvenor is a pretty quiet place in the middle of the afternoon. “I screamed as loud as I could and as often as I could when I was down in the hole.”

But no one heard him. Finally after a few tries, he said he was able to leverage himself back up on to the platform. “I personally don't want to go through this again. And I don't want anyone else to go through it again. It's a frightening experience.”

Some of the 7000 series cars already have the old chains between them. And Metro says it will now install them in all the existing cars by the end of next year.