New York City ? Human bones unearthed at the World Trade Center site in recent days are so well preserved that they will yield usable DNA, experts predicted Wednesday.

The remains – found last week after utility crews doing routine work opened a manhole that had been paved over – are believed to belong to Sept. 11, 2001, trade center victims, 40 percent of whom have not had any remains identified.

The collection has grown to nearly 200 pieces, including whole bones, shards and 1-inch splinters.

“However they got there, it was certainly right at the time of the event, so they’ve been protected for five years and haven’t been subjected to weather,” said Bradley Adams, the city medical examiner’s lead forensic anthropologist on site.

Bones buried with no exposure to extreme temperatures tend to be better preserved, said Ed Huffine, the head scientist on the project at Bode Technology Group, the Virginia company handling 9/11 bone fragments.

“I would be very optimistic about being able to obtain DNA profiles from these cases,” he said.