OBJECTS HITTING

trains nothing new.

The possibility that a flying object hit an Amtrak train moments before it lurched off the rails Tuesday in Philadelphia has unnerved riders and drawn increased public scrutiny to the safety along that stretch of track. But federal and railway officials say being struck by rocks, bricks and even bullets is a long-standing problem for trains in the country’s rail systems.

Amtrak trains are pelted often enough that engineers have a term for it, said Doug Riddell, a retired Amtrak engineer who lives in Ashland, Va. They call it getting “rocked,” he said.

“The problem is common enough that what happens is you pick up your radio and say: ‘I got rocked up there. Watch yourself,’” Riddell said.

He also said engineers often exchange a warning: “There’s kids in the tracks up there. Watch out.”

Investigators have not assigned a cause or blame for the crash of Amtrak’s Northeast Regional train No. 188 as it made its way to New York from Washington. Eight passengers were killed and more than 200 people, including members of the crew, were injured. The train’s engineer told investigators that he had no recollection of anything after passing the North Philadelphia station.

Investigators have said the train was traveling at 106 mph — more than twice the posted speed limit — moments before the crash. They announced Friday that they had found a fist-size circular area of impact on the left side of the train’s windshield. Officials said the FBI had been called in to help with a forensic investigation.

Around 9:10 p.m., just minutes before the Amtrak crash, an unidentified projectile shattered the windshield of a regional train operated by the Southeastern Pennsylvania Transportation Authority shortly after that train left 30th Street Station in Philadelphia, authority spokesman Jerri Williams said. The engineer stopped that train on the tracks about 2 miles south of where the Amtrak train derailed.

Williams said the authority’s trains are often hit with rocks and other projectiles but that Tuesday night’s incident was different because the damage forced the engineer to take the train out of service. Police were called to the scene, and the passengers were escorted off the disabled train. There were no serious injuries.

The Southeastern Pennsylvania Transportation Authority has been working with its own police force and the Philadelphia police to try to prevent the throwing of rocks or other objects, Williams said, but stopping it is complicated by the proximity of the tracks to urban neighborhoods.

“There’s overpasses and tunnels that people can go over and under,” she said.

As officials looked into whether this old problem may have played a part in the Amtrak crash, federal officials were taking steps to try to reduce the chances of a similar accident along the stretch. The Federal Railroad Administration announced Saturday that it has instructed Amtrak to expand the use of technology that would stop a train if it is going too fast and the engineer fails to respond to warning systems.

Reports of trains being struck by objects near the North Philadelphia station happen about two or three times each month, Southeastern Pennsylvania Transportation Authority’s Williams said. She said she did not know what motivated people to throw things at trains.

“The objects are thrown by vandals who are sometimes children,” she said. “The objects are sometimes rocks.”

A federal official familiar with the Amtrak inquiry, who spoke on the condition of anonymity, said officials had seen the hole in the Amtrak locomotive windshield earlier in the investigation but that some had assumed it was damage from the crash or perhaps the result of the engineer smashing into the windshield during the crash.

Typically, reports that something has been thrown at a passing train are no cause for concern, a senior federal transportation official said. So if that or a fired shot is proved to be the cause of the Amtrak crash, it will open up “a whole new load of stuff for us to be worried about,” the official said.

Alfred Price, 32, a documentary filmmaker, said he was sitting on the Southeastern Pennsylvania Transportation Authority train that was struck Tuesday night, just three or four rows behind the engineer’s booth, when he heard a “loud boom.”

“It sounded like a mini-explosion from underneath the train,” Price said. “You could feel the train rock back and forth erratically, which wasn’t normal. Then the train stopped.”

Minutes later, Amtrak 188 train passed them by.