It's an assembly line in reverse, retired MTA buses getting stripped piece by piece so the transit agency can sell off the parts and scrap. Transit Reporter Jose Martinez takes us inside the Bronx Depot where buses truly reach the end of the line.

MTA Bus 6137 is coming off the road after 16 years and more than half-a-million miles carrying New Yorkers along the city's rugged streets.

"That's hard driving, for sure," said Frank Annicaro with the MTA's Department of Buses.

But this bus, built in 1999, is headed for a retirement that's anything but quiet.

Its number and depot seal are scraped away, its tires removed, its fluids drained and its seats stripped. So many of those parts can be used again.

"It could be panels, body panels, it could be glass or windows," said Steven Boscarino with the MTA's Department of Buses.

Even the antifreeze and diesel fuel drained from the retiring buses get repurposed.

"We do not send any of our buses to the recycling program with any fluids at all," said Annicaro. "All of the fluids are recovered and recycled. There is no introduction into the waste stream."

Number 6137 is one of more than 500 buses that will be cannibalized and recycled this year at the MTA's Eastchester Depot, which doubles as a kind of legal chop shop.

"It's an involved process and environmentally, the buses that we bring here, the material gets recycled, the metal gets recycled, so that's environmentally friendly and you're not putting stuff in the waste stream. And it's a win-win," Boscarino said.

After recycling bus parts - many which are put back into the existing fleet of more than 5,000 buses - the MTA generates about a million dollars a year by selling what's left as scrap.

"It's just metal," said Annicaro. "It's metal that's reintroduced as refined and turned into other metals."

After years of venerable service on the road the end comes quickly for the buses.

On average, buses stay in service 12 to 15 years. But it takes just four hours to get them ready to be scrapped.

And soon, bus number  6137,will be just a memory.